LOL. Not to get you worried, but carfax and all the VIN based reports are not what they advertise to be.
For example, last year while I was hunting for a VX, I got myself one of those accounts that would get me 20 VIN reports. Since that was more than I needed I ran the VIN from my GTi and a friend's car just to see how accurate they were. None of our reports showed that our cars were registered in California for any period of time. The reports only showed Oregon registration where both cars were purchased and registered for 3 years before registering in CA and then back to OR after 2 years in CA. Both cars had been broken into (with repair bills well over $5000 per car) more than once and none of that was on the record. Mine was rearended once, though not serious, the incident was not shown in the report. Odometer readings were also not kept current. Only two readings (over 4 years old) were on record.
I think the better thing to do when buying cars is either to check it out personaly, or have one of those pre-sale vehicle check services check the car out for you. I didn't do that figuring my VX was new... but as it turned out, there were defects. As navigator mentioned, those reports are only as good as the data available (and in most cases, not much is available.) It's a good thing in a way... it shows that your privacy is being safeguarded to a certain extent.