Roof: Type of construction: ABS, Alum over wood, etc. Joints: well caulked/sealed. Gaps? Water damage. Buckling/dips in roof.

Floor: type, condition, rot? (get under it and look for wet marks, stick utility knife in it and check for soft spots), rust, cables, gas lines, electric wires.

Canvas: condition of canvas, zippers, windows. Look for wear, tears, holes, rodent damage, etc. Do all zippers operate well? Any broken teeth. How tight is it? How does it attach under the bunk ends? Look were it attaches to the roof. Any screws pulled out or missing? Any staples pulled out? How about where the shepards pole attaches to the roof if it attaches through the canvas.

Plastic in windows good condition? Any scratches, tears. Stitching connecting it to canvas? Cloudiness?

Cushions: condition. Smells? Rodent damage? Thickness. (Remember, all cushions can be recovered or replaced.

Curtains: included? Condition? Do they run on their tracks well?

Appliances: do they work on all fuels/energy options? Turn them on and see. Don't take anyone's word. Take a thermometer along for AC, Heat and Fridge. (Wireless is most convenient).

On board water system: storage tanks, plumbing lines, was it winterized properly? Have owner fill up system so you can see there aren't any leaks. Make sure water pump and water heater work.

Septic system? Gray and black tanks? Check for leaks. Do level indicators/lights/sensors work? (Make sure they are empty before you take delivery. Nasty to have them not empty. Ick.)

Exterior: type of material. Condition. cracks/leak areas. Does roof and box seal? there will be water damage if not, especially at front wall and roof and possibly lift posts.

Lift posts: operational, condition.

Winch/lift system: How hard does it turn to lift? Where do cables run (interior or exterior under floor)? Maintenance?

Towing lights: All work? Any broken. What about sealed to box?

Tongue: how hard to hitch up? Front jack operational? Battery? Chains?

Stabilizer Jacks: Type? Quantity? condition? Any bent?

Electrical: converter, 30 amp cord, plug end.

Tires: check condition and wear patterns and proper tire inflation.  Was the tires on it all winter? Outdoors?  On the soil, or up on wood or cement or stones?  Spare included?  It's condition?  What do you need to get the lug nuts loose?  Special wrench?  Wrench from your tow vehicle?  How old are they?  Is there any dry rot or cracks in the side walls.  Remember, these tires are NOT made to go as fast as the ones on your tow vehicle and if improperly inflated, will fail rather quickly, leaving you trying to change that along the roadside.

Does the seller know how to operate everything?  Make him show you how to do it all. Put pup up and down. Light and run everything.