The fastest way to spot a bad used RV is to ask twelve specific questions and watch how the seller reacts. A good unit survives the questions; a hiding one gets vague, defensive, or suddenly "in a hurry." Below is the exact list, what a good answer sounds like, the dollar range each problem can cost you, and the lines where you should walk away.
A used RV is not one purchase. It is a house and a vehicle bolted together, and both halves can rot, leak, or quietly die while sitting in a driveway. The seller knows the unit's history. You do not. These questions are designed to close that gap before money changes hands, and to make silence and dodging show up loudly. Ask them out loud, in person if you can, and write the answers down. When you are ready, you can paste the listing and get your RV verdict for a second opinion on the numbers.
How to use these 12 questions
Work the list in person, with the unit in front of you, on a dry day if possible (rain hides leaks, sun reveals them). Ask the question, then stop talking. The pause is where honest sellers fill in detail and nervous sellers start managing you. You are not trying to be a jerk. You are trying to find the one or two problems that turn a fair deal into a five-figure mistake.
A quick scoring rule before you start: any single "I'm not sure" on water, title, or frame is a pause, not a deal-killer. Two or more vague answers in those three areas, and you walk. RVs are common and patient. The next one is a week away.
Questions 1 to 4: water, the thing that kills RVs
Water intrusion is the number one destroyer of used RVs, and it is mostly invisible until it is catastrophic. These four questions all circle the same enemy.
1. "When was the roof and all the seams last resealed, and do you have the receipt?" RV roofs need resealing roughly every year at the seams and a full reseal every 8 to 10 years. A good answer names a date and a product (Dicor lap sealant, Eternabond tape). A bad answer is "it's never leaked, so I never touched it." Resealing is cheap insurance; a roof that has never been maintained on a 10-year-old trailer is a real risk. Budget $200 to $600 for a DIY reseal, or $800 to $2,500 for a professional job. A full roof membrane replacement runs $300 to $400 per linear foot installed, so a 30-foot trailer can hit $9,000 to $12,000. Learn the tells on our roof leak signs page before you climb up.
2. "Has this unit ever had water damage, soft spots, or delamination, and where?" Ask it plainly and watch the face. Then verify with your hands regardless of the answer. Press on the floor near every slide, the entry door, the corners, and under windows. Soft, spongy, or bouncy flooring means the subfloor is rotting underneath. Look down the exterior walls at a low angle in sunlight: ripples, bubbles, or waves in the fiberglass are delamination, where the outer skin has separated from the wall because water got in. A soft floor repair is typically $1,500 to $6,000 depending on how far the rot spread; serious delamination across a wall can exceed $5,000 and is often not worth fixing. Know the full pattern at RV water damage signs.
3. "Can I see inside every cabinet, the wardrobe, and the back of the under-bed storage?" Water hides where buyers do not look. Open everything. You are hunting for stains shaped like drips or rings, a musty smell, blistered wood, or fresh paint that is covering something. A musty odor that hits you when the door first opens is a major red flag, because it means moisture has been living in the unit, not just visiting.
4. "Have the slide-outs ever leaked, and can we run each one in and out twice?" Slides are a top water entry point because the seals wear and the roof of the slide collects debris. Operate every slide fully, both directions, twice. Listen for grinding, watch for jerky or uneven travel, and inspect the seals and the floor at the slide opening. Slide-out problems range from a $300 seal replacement to $2,000 to $5,000 for motor, gear, or mechanism repair. If a slide will not move at all during your visit, treat that as a walk-away until proven otherwise.
Questions 5 to 7: title, history, and what's been hidden
5. "Do you hold a clean title in your name, and is there any lien on it?" This is the question that protects you from buying someone else's loan. If there is a lien, the lender holds the title and the seller cannot legally transfer ownership free and clear until it is paid off. Never hand over full payment for a lien-encumbered RV without the lender directly involved in the payoff. A seller who gets cagey about the title, offers a "bill of sale only," or has the unit titled in someone else's name is a hard stop. Run the VIN yourself; see title and lien check for how.
6. "Why are you selling, and how long have you owned it?" Listen for the story behind the story. "We're upgrading to a fifth wheel" is normal. "We barely used it" on a unit with obvious wear, or a seller who bought it four months ago, can signal a flip or a problem they discovered. Short ownership plus a fresh, glossy listing photo set is a flip pattern: someone bought cheap, hid the issues, and is selling fast.
7. "Do you have service records, and has it ever been in an accident or flooded?" A binder of receipts is one of the best signs you can find. It means the owner cared and documented. No records at all on a 10-year-old motorhome is not automatically disqualifying, but it shifts all the risk onto your inspection. Flood history is especially important on any unit from a hurricane or flood region; flood-damaged RVs develop electrical gremlins and mold for years.
Questions 8 to 10: the mechanical and big-ticket systems
These three target the components that cost the most to replace, and they apply differently depending on whether you are buying a towable like a travel trailer or fifth wheel, or a motorized rig like a Class A or Class C motorhome.
8. "How old are the tires, and what's the DOT date code?" RV tires age out before they wear out. Most should be replaced at 5 to 7 years regardless of tread, because the rubber degrades and blows out, often taking fender and wall damage with it. Read the DOT code on the sidewall: the last four digits are the week and year (for example, 3819 means week 38 of 2019). Six tires on a fifth wheel run $1,200 to $2,400 to replace; motorhome tires can be $400 to $700 each. See tire age for how to read the codes and budget.
9. "On the generator, how many hours are on it and when was it last serviced and exercised?" A generator that sits unused gums up and fails. Onan and similar units want to be run under load monthly. Low hours are good only if the unit was exercised; a generator with 30 hours that sat for five years can be in worse shape than one with 500 well-maintained hours. Check the hour meter and ask about oil changes. More on reading the meter at generator hours.
10. "Can we power up every 12-volt and 120-volt system right now?" Insist on a live test with shore power connected and the batteries in. Run the AC, the furnace, the water heater on both gas and electric, the fridge on both modes, every light, the water pump, the awning, and the leveling jacks. Anything the seller "can't demonstrate today" is something you are buying blind. Soft or dead house batteries are common and cost $150 to $1,500+ to replace depending on whether it is flooded lead-acid or lithium. Deeper faults show up at RV electrical problems.
Questions 11 and 12: weight, fit, and the real price
11. "What is the exact dry weight and GVWR, and what's the hitch or pin weight?" This is the question that stops you from buying an RV your truck cannot legally or safely tow. Get the numbers off the yellow sticker on the unit, not the brochure, because options add hundreds of pounds. Then run them against your tow vehicle. A trailer that exceeds your truck's tow rating or rear-axle limits is a deal-killer no matter how nice the kitchen is. Use our towability calculator with the real sticker numbers before you commit.
12. "What's your best out-the-door price, and will you stand behind a pre-purchase inspection?" The price question is also a character question. A seller confident in the unit will welcome a third-party inspection (typically $150 to $500 for an RV inspector, money very well spent). A seller who suddenly objects to an inspection, or pressures you to decide today, is telling you something. Anchor your offer to real comparables, not the asking price. Our used RV offer calculator helps you build a number you can defend, and the ownership cost calculator shows what the rig actually costs per year once you own it.
The 12-question scorecard
Print this, take it to the viewing, and fill it in as you go.
| # | Question targets | Good answer | Red flag | Typical cost if wrong |
|---|---|---|---|---|
| 1 | Roof / seal history | Dated reseal + receipt | "Never needed it" | $800 to $12,000 |
| 2 | Water damage / soft floor | "No, and here, feel it" | Vague or defensive | $1,500 to $6,000+ |
| 3 | Hidden moisture in cabinets | Clean, dry, no smell | Musty odor, fresh paint | $1,000 to $5,000 |
| 4 | Slide-out leaks / operation | Runs smooth both ways | Won't demo, grinds | $300 to $5,000 |
| 5 | Clean title / lien | Title in hand, no lien | "Bill of sale only" | Walk away |
| 6 | Reason for selling | Honest, consistent story | Short ownership + flip vibe | Varies |
| 7 | Service records / accidents | Receipt binder | No records, evasive | Risk shifts to you |
| 8 | Tire age (DOT code) | Under 5 years | 7+ years, cracking | $1,200 to $2,400 |
| 9 | Generator hours / service | Exercised, oil records | Sat unused for years | $1,000 to $4,000 |
| 10 | All systems live test | Everything runs now | "Can't show today" | $150 to $3,000 |
| 11 | Weight vs your tow vehicle | Sticker numbers fit | Over your rating | Deal-killer |
| 12 | Price + inspection | Welcomes inspector | Refuses, rushes you | Overpay $2,000 to $10,000 |
Walk-away conditions: the non-negotiables
Some answers should end the conversation no matter how good the rest of the unit looks:
- The seller will not let you inspect the roof, the floor, or run the systems live.
- There is a lien and the lender is not part of the transaction.
- The title is not in the seller's name and they cannot explain why.
- You find soft, spongy floor plus an exterior wall that ripples in the light (water plus delamination together).
- The frame or A-frame shows cracks, fresh welds, or heavy rust on a fifth wheel or travel trailer.
- The seller pressures you to decide today or skip the inspection.
Everything else is a negotiation. These six are exits. For the full visual rundown, keep our used RV inspection checklist and RV red flags open on your phone.
Match the questions to the rig you're buying
The list above is universal, but weight the answers by type. On a Class A motorhome the chassis, generator, and slide systems dominate the risk and the repair bill. On a travel trailer or fifth wheel, the frame, axles, tires, and roof matter most. Brand reputation also shifts the odds; if you are comparing models, our pages on Forest River, Keystone, Jayco, Grand Design, and Winnebago cover the known strengths and recurring complaints by maker, so you know which questions to lean on hardest.
Frequently asked questions
How long should the 12 questions take at a viewing? Plan for 60 to 90 minutes on the unit. The questions are fast; the verification (feeling the floor, running every system, reading tire codes, photographing the title) is what takes time. If a seller will not give you that window, that is itself an answer.
Should I still pay for a professional inspection if the answers all check out? Yes, on anything priced above roughly $10,000 or any motorized RV. A third-party RV inspection runs $150 to $500 and routinely finds $2,000 to $8,000 in issues a buyer missed. It is the cheapest insurance in the entire purchase.
What's the single most expensive thing these questions catch? Hidden water damage and the rot it causes. By the time soft floor and delamination are visible, repair often runs into the thousands, and a fully water-logged rig can be a total loss. Questions 1 through 4 exist to catch it before your money does.
The seller answered everything well but won't budge on price. Now what? A clean unit at a firm price can still be a good buy. Anchor your decision to comparables, not your hopes. Run the asking price through the used RV offer calculator and the ownership cost calculator so you know whether "firm" is fair or just stubborn.
Do these questions work for buying from a dealer too? Yes, with one change: dealers will have polished answers, so lean harder on documentation and the live systems test, and still insist on your own inspection. A dealer's reconditioning does not replace your eyes on the floor and roof.
Ready to pressure-test a specific unit? Paste the listing and get your RV verdict.