http://www.consumeraffairs.com/autom...fax_inacc.html
I just read a few reviews in there and it appears even if the CARFAX was clean when you bought it, it doesn't mean anything later as accidents mysteriously appear. There are reviews where a car is 100% not in an accident and the CARFAX shows it was.
Maybe that's what you are dealing with? I'd bring it into a body shop and have them comb it over and see what's what.
Basically it sounds like CARFAX is not reliable at all. Even though I vaguely remember looking at the screen for Car fax when I bought mine a few months ago,
I'm going back in to see the one on my car again and check as mine had 3K miles on it when I purchased.
Good luck with everything.