Look down the sides of the RV for waves in the walls. This could be from delamination, which is a major problem. While you're at it look for dents, scratches or dings. If the marks are not bad they can often be overlooked.
Look for warped or stained interior walls and ceilings, especially in the cabinets and corners. Look for soft spots on floors or around windows and vents. This could be a major expense to repair.
Walk through the unit before purchasing it to be sure everything works. If appliances or doors do not work, consider how much it will cost to repair the problem.
Check the bathroom. Is it big enough for you? Take a pretend shower and sit on the toilet to make sure there is enough room for your legs.
Test drive the unit. Listen for noises, belts slipping, banging or any unusual sounds.
Check under the hood with a mechanic if you do not have knowledge of engines.
Crawl under the unit to check for leaks, suspension problems, hoses and wire connections.
Check with your insurance company to make sure its insurable or that there are not any other problems. Be careful about the weight that repairs might add to the motorhome.
