There is a woman who found a way to game casino black jack and made millions out of it before getting caught. It's nearly impossible to replicate but it involved spotting imperfections in the way print sheets are cut up into individual cards.
I don't remember her name but she was an associate of poker legend Phil Ivey, and there's a whole documentary on YouTube about it. It's pretty fascinating what greed and a ridiculous level of risk tolerance can achieve.
Greed and cheating needn't be realted. The players are following this strategy to make money, presumably more than they should want. Whether they're taking it from moral or immoral sources should be a separate issue, imho.
They were actually changing the deck in way that survives shuffling, not just looking at the differences.
They were using the offset on the printing as a way to tell orientation of the card. Since auto shufflers never rotate the cards, any rotation they added would persist allowing a way to tell good from bad cards in future hands.
Yes that is why I mentioned it was nearly impossible to replicate. The final optimized method involved a lot of social engineering, which required to have very high standing in the casinos. She had to request, under the guise of superstition, a specific setup with a specific style of dealer, who never changed decks, and to be authorized to call out certain cards as "lucky" which the dealer would flip themselves.
It also required deep pockets, as just playing the shoe enough to sort it could take a few hours of regular gambling. That's the crazy thing, this elaborate setup just got them a few % edge on the house which they milked relentlessly.
I don't remember her name but she was an associate of poker legend Phil Ivey, and there's a whole documentary on YouTube about it. It's pretty fascinating what greed and a ridiculous level of risk tolerance can achieve.