The important thing is to inspect the unit yourself *thoroughly for leaks. If you see ANY indication of water intrusion then move on to the next rig - there's lots of them out there.
I traded in a TT that had rot under a window of which I told the dealer about. He didn't care. Did he tell the next customer? I doubt it.
Don't trust them!
*Step inside RV, does it smell musty? Open every cabinet and look for stains on ceiling. Step in every corner, esp. bathroom, and check for softness of the floor. Look for any odd staining of the linoleum. Go up top of the roof and look for soft spots. Check exterior compartments for mustiness, water stains or softness.