Mlsstl, If you were asking me how I know it happens, I have had it happen to me. A dealer sold me a cd player, didn't mention that it was B stock. Someone who knew the dealer better told me it was B stock after I had problems with it.
I returned it twice under warranty and after the 1 year warranty ran out the fourth one conked out. I threw it away and got a different player. That's how I know.