The caveat though (at least in my mind) is that you have to consider [MENTION=442798]bulldog1935[/MENTION]'s comment that "there are many ways to produce undetectable matrix damage in composite," or [MENTION=350383]crank_addict[/MENTION]'s statement that he "crashed a few times..." That makes me shy away from used CF bikes.

We have all seen steel bikes for sale with obvious front end damage. It's obvious because the crash pushes the fork back a bit, and you can often feel ripples under the down tube or see cracks in the paint. Even with that damage, many of those bikes can either be ridden as-is, or have their forks straightened, and maybe have their head tubes pulled back out. (My Medici is one such example.) Most of us have at least some seat-of-the-pants understanding of the properties of steel which make this possible. Where is the visible warning of a past crash in a carbon fiber frame?