A CarFax report is just ONE piece of information.
A few months ago, I saw a a one-owner, Certified Pre-Owned 2011 Town and Country-L van, that only had 30k on the odometer. The CarFax didn't show any negatives. Regular maintenance/oil changes, no wrecks.. all looked fine from there. It was a Chrysler Certified Pre-Owned vehicle as well.
Between it being a one-owner, with good CarFax, and CPO certification... I assumed that I'd found my van.
However, when I saw it, that van had huge issues. I just didn't walk away... I ran as fast as I could. If it wasn't low miles and qualified for CPO, the dealership would have sent it to the auction without a second thought.
It was filthy dirty on the inside. The windshield was scratched, the leather on the driver's seat was already starting to crack and split open, it had about $800 in paint damage on one fender (it was starting to rust as well), no manuals at all, the front bumper cover had been run up and over a tall curb multiple times, and was now pulled loose from its mountings (and was scratched and gouged on the underside), and one door was filled with light door dings, all in a row (apparently, it had the same vehicle parked next to it all the time).
But hey... the CarFax report looked great.