That's actually not a bad hustle but it's VERY risky. On a side note, how were they able to play the free play without the pin? Surely they don't know complete Stranger's pin numbers, especially when the pin is a six digit pin like Gulfstream Park Casino does. If you had said the Hustlers were purposely leaving THEIR own cards in the machine and hoping random people play on their cards inadvertently earning them the free play and then came back after the random Stranger lost all their money and left, that would make a lot of sense. In two of my local Casinos, there is like a 30 minute window before the card has the "Session abandoned," thing. In my other local Casinos, the window is only like a five minute window before the "Session abandoned," thing comes up. So theoretically a Hustler can purposely abandon his card in the still active machine and let some random stranger play and lose on his card and earn him the free play and then come back and start playing on his card again and get the free play. A 30 minute window is extremely generous.