Phil Ivey wins a huge amount of money playing punto blanco in a British casino. They refuse to pay him because they say he cheated. Their claim? That he noticed flaws in the print of the cards and used that knowledge to win.
How is that cheating?
He did not alter the cards. He did not hid cards up his sleeves. He noticed something that the casino failed to notice and used it to win the game. The casino put the cards out to play with.