This doesn't always work.. I ran a frame number through this once and nothing came back on it so i bought it, Had it sitting in the shop starting a build on it had the DNR officer come over to run the numbers to get a title and what do you know it came back stolen when the officer ran the numbers.

Not sure how well this works either.
I have a 1987 Monte Carlo SS Aerocoupe that was stolen from me a while back, and I bought what was left back from the insurance company just because of the back window alone.  So, I know it has a stolen history and it is now on a Total loss/Salvage title.

Its VIN came back on this site as clean.  No theft record and no loss record.

So, not sure on its accuracy.

Just my .02