As soon as a player took a goofy hit, the whole rest of the shoe would be off. If you think they're cheating, hit a 19, and then you'll get all the other guy's cards.
I'd worry less about a shifty shuffler and more about a shifty deck of cards being fed in. Hold out a few cards from the deck and you could improve the house's chances.
Most new-generation shufflers have built-in deck-checking code. If the cards in the shoe aren't what they're supposed to be, the shuffler errors out and won't deal at all.
So it knows there should be, say 6 9's of diamonds?
Those are electronic shoes. They do not know the sequence of the cards, but can read them as they are being dealt.Quote: WizardofEngland
EDIT the new shoes can also 'count' and signal the pit when the count it favourable for the player, then they just look for high bettors.
If dealer and player hands are dealt from separate decks, as I believe they are in a few places (Pennsylvania?) the task becomes much easier.
Another one I don't believe!! Separate decks of cards for the players and the dealer?? Can anyone verify this one?