If buying used, check it out closely, bring knee pads, lighting, thermometer, IR gun, maybe a moisture meter. Get under the coach and look over every inch of it, take pictures, videos. Take your time do the same thing inside. Then the roof. Test drive, check the engine compartment coolant, oil, brake fluid,transmission fluid, drive shaft, tires and date codes, awning, steps, appliances, all windows, lighting in and out, heating and cooling system, all systems, generator, oil. You can actually send the engine oil out for analysis as well. Mirrors, hitch, batteries, water tanks, propane tank, charging systems, bring a multi-meter. Leveling jacks, go slow while inspecting, etc. If you are not comfortable doing this have a professional inspector see it. Good luck.
2001 Itasca Suncruiser 32V F53