I see this posted quite a bit by people on web forums, but it's simply not true. If the buyer paid fair value for the property and was otherwise innocent in the transaction (i.e. they didn't know the seller didn't have the right to sell it - or it was stolen), then they are likely going to be deemed to be a bona fide purchaser.
http://legal-dictionary.thefreedicti...fide+purchaser
http://financial-dictionary.thefreed...fide+purchaser
There may be other laws governing this issue as to particular persons or entities, such as pawn shops or other commercial places, but to the average Joe this is a remedy that allows him to keep the property that he paid for. The original owner must sue the thief/seller for damages, and cannot come after the BFP.