Anyone interested in this would do well to read Gambling Scams[1] by Darwin Ortiz and How to Cheat at Everything[2] by Simon Lovell. There's also an interesting Real Hustle episode where they manage to cheat their way in to winning a high stakes game against some famous professional poker players.[3]

The books mentioned above talk in detail about cheating methods in all sorts of games, not just poker, and have solidified my own determination to never gamble for money. It's way too easy to be cheated -- and the cheaters don't need any high end devices to do it either. Plenty of methods are very simple, very cheap (if you don't count the medical, legal, or funeral bills if you get caught), and very effective.

[1] - https://www.amazon.com/Gambling-Scams-Detect-Protect-Yoursel...

[2] - https://www.amazon.com/How-Cheat-Everything-Simon-Lovell/dp/...

[3] - https://www.youtube.com/watch?v=63jgfmgqkO0