Take an icepick or similar sharp object and check the floor in the rear "if you can " about 3 to 4 inches in from the wall ,this is a common spot for floor rot but it is very repairable ,the other place to look for floor rot is around the front window area esp under the vista windows ,again its not the end of the world if it is rotted it is fixable also ,check to make sure the tambours are all in tact ,ask if the gas bottles have been updated ,check the axles make sure they or it has not sagged past 0 deg there is a good explaination of this on Andy's site at
http://www.inlandrv.com , dont let these things scare you .......just be aware of them . I hope this helps Tom