I was looking for a good used car for my 17 yr old son on craigslist and you wouldn't believe how many scammers there are. Lot of cars have salvage title or rebuilt and with car fax I could tell how many owners there where and for how long they had the car for. About 50% of cars for sale by owner was wanna be used car sales hustler listed "for sale by owners" When I question them using car fax data they either hung up or made stupid excuses like: Oh its by girlfriends car or im just selling it for a friend. CarFax data if used right is a powerful tool to weed out the good cars from the bad