Buying used RVs can be a much better deal than getting brand new ones because they are, in general, more affordable while still offering the same nifty features and amenities. However, this all depends on how well you’ve inspected the unit before purchasing it. Some RVs may be sold for cheap, but they could burn a large hole in your finances with the repairs that they need to function well.
Check the flooring, walls, cabinets, and any other surface for signs of water damage. This might be caused by leaky plumbing in the RV, or a worn and broken AC. You should also check the water lines themselves; if they look like they have been recently replaced or repaired, step on the floor right underneath them to check for soft, water-damaged spots.
Check the propane tanks to ensure that your prospective RV is using the more modern and safer models, and not the old brass connector types with large threads on the outside. If it happens to be the latter, at least look for tanks with reliable alarm systems that should warn you of potential gas leaks.
Look at the tires and check if they are worn. This will give you a good idea of how much the unit was used by its previous owner. While you can always get replacement tires, a run-down vehicle might need a lot more repairs than you’re capable of paying for, so be sure to double-check.