Check out the plastic, the frame, the tread on the tires, switches, wheels, after-market parts, a-arms, brakes and everything visible. Make a note of heavy scratches, loose parts, and things that are clearly damaged. Ask questions about use, and problems the owner has encountered. Hopefully, you will get some honest answers. Either way, if it looks good enough to buy ask to take it for a test drive. If they refuse, go ahead and start looking elsewhere. If you are able to test ride it, I'd test everything out. Ride it like ur going to at home, without rolling it over of course. Welcome to HQ and happy buying!!