Can not agree more with JimmyJames here... I have always told friends and family to NOT put their trust solely in a CarFax report.

Bottom line, CarFax should be one of the many tools on your "virtual tool-belt" that is used when purchasing a used vehicle. If you don't feel comfortable that you know how to spot repaints, frame work, and other tell tale signs of a damaged vehicle on your own... do yourself a favor and hire an independent contractor to do a thorough inspection FOR you.

It's just plain common sense.

EDIT: Actually I have a great story to go along with this...

My brother purchased a BMW 325i in South Florida a couple of years ago (that should be warning sign number 1... lots of good guys down there and a far greater number of BAD ones... this dealer was called Carstrada) that had a very very clean AutoCheck or Carfax. So he brings it home to me when I was living in Tampa. At first blush the car looks great, but then I start looking closer and IMMEDIATELY see signs of damage on the valance that clearly showed the valance had been repaired and straightened. I tell him to take the car back and get an exchange or a refund.

Well they obviously didn't want to give him a refund so they gave him another car, a 2005 Volvo S40 that looked even better when he brought it home. But after looking more closely there were clamp marks on the underside of the car. Turns out that these Carstrada guys bought AND turned the car in such a short amount of time, that the AutoCheck indicators that would show it was purchased at a repaired vehicle auction hadn't even had time to appear yet! A couple of months later the data showed up on the Autocheck. You just can't do enough due diligence when purchasing a used car.