You can have leaks any where, start with roof, note where each roof opening is then check inside, check where front and rear caps meet roof and side walls. Push on walls, should not be soft. Check date on batteries and date code on tires (5 to 6 yrs max) even if tread looks good, you'll end up with a blow out. Tell the guy to have the a/c running and the refrigerator running before you get there, then switch over to lp when you get there (can cost up $1200-1500 for new ref.). If you smell rotten eggs you may have a bad ref. Also make sure water heater works and has not burned the grill. Use your nose for mold? Look for someone who did there own repairs where wiring goes to no-where. Hook up the water and run all of the faucets inside then look for leaks below the floor. Walk on every square inch of the floor looking for soft spots, if you find any soft spots run or expect to get $2 to 3 k or more off the price (if you want to do the repairs). Installing new flooring, changing out the valances, and even changing fabric can always be done years later. You want a solid rv to start with. Ask for service records, if they don't have any, they may not have done any. You best change of getting a really nice rv is to find one that has been inside a covered storage. The paint will be nicer and the fabric will not have faded, expect to pay more. You can also hire a professional inspector if you want. Good luck.