checking the condition of the paint in obscure/out of the way places such as in the wheel well and generally anywhere there is paint that isn't on the top or sides can give you a good indication of whether it's been a wreck and had large components replaced with parts from other cars, then [sometimes sloppily] repainted. This isn't necessarily a bad sign, but if they don't own up to the wreck, then it throws doubt on their character.

or so my dad said once