There is a time delay between a car getting sold at auction and when the Carfax is updated. If a dealer is the winning bidder on a car that will have issues when the Carfax is updated, he will run a Carfax immediately after buying it so the report still looks clean. Carfax won't show repairs if the car owner is self-insured. Especially true with rental cars and other fleets. My friend worked at a dealership and the used car manager bought several former rental vehicles at auciton. Every one of them had a clean Carfax and chassis damage.

Too many title flips close together means the first dealer got stung by the prior owner (probably shoddy off-the-books repairs) and he tried offing it to another dealer. Years ago, my neighbor got in a bad wreck with a 2-year-old Mercury Sable. His brother the backyard bodyman put it back together (can you say 'gallons of Bondo'....). My neighbor promptly traded the car in on a new one. I heard through the grapevine that the dealer really got screwed on that deal.