Don't be blinded by a clean CArFAX either, Just because nothing is there does not mean no accident; I suppose CArfax is just a negative indicator - nothing there means you have to look at it, if there is something showing, then you know where to look for the damage.
I looked at a 91 NA1 that was billed as a pristine garage queen - clean CarFAX, and found ill fitting panels, non stock hardware, wrinkled welds and an aftermarket paint job. Would be great for a track car (if no frame damage) but not in my garage.