I've noticed that at the large flea market here, the further you go down the outdoor aisles, the vendors are grubbier, have less teeth, more tattoos, and I keep hearing fiddle music.
My best flea market find several years ago was a JP Sauer 1939 Mauser all matching except for the bolt which was all matching itself no import stamp of any kind. I made my wife stand there and hold it while I found a ATM to get the $150 the guy wanted.
When you see an empty S&W box for sale at a flea market better ask where is what came in the box. It is usually in the cab of the truck and yes it is for sale.