I believe most of these 'professional' slot players operate around the multi-machine jackpots which can sometimes get large enough to offer a positive EV on the

I believe most of these 'professional' slot players operate around the multi-machine jackpots which can sometimes get large enough to offer a positive EV on the games. They work in teams though admittedly is been a long time since I've read about it. There was also another guy I read about who worked on finding flaws in the prngs and pay tables but those would only last a matter of months before corrected.