I would say that it is very good at picking out questionable history. I

Well, that depends. I also ran Carfax on my '84 that I bought off eBay. The seller stated that it came from Houston Texas, which Carfax confirmed. The seller also told me the person who sold it to him had rebuilt the engine. Carfax showed it failed emissions testing in Texas in 1997, and passed emissions two years later in 1999. The mileage between '97 and '99 only increased by 500 miles, indicating a *possibility* the engine was rebuilt. Carfax did NOT  show any accident history. However, the entire front drivers side is sculpted from bondo, and the impact strip behind the "decorative" front bumper has been cut and mangled. So, if a vehicle has been wrecked, and no police report filed, Carfax isn't going to pick up on it. My guess is either the owner didn't have insurance, or maybe it was a single vehicle accident (hit a tree) and the owner didn't want insurance involved, and paid a crappy body shop to do a crappy, cheap repair. Yeah, the  Carfax report is nice to have, but as I found out is not a 100% guarantee of a good vehicle.  Jeff