One line of reasoning goes like this:
1. Gambling is illegal.
2. Gambling can be made legal under certain conditions - for example, in a licensed casino for certain games under certain rules.
3. In those cases where the gambling is done in a licensed casino, in a regulated game, and under the rules established, gambling becomes a lawful activity.
4. In the absence of those conditions, the gambling remains illegal.
5. Winners of illegal games have no right to their winnings. (in fact, under pre-casino law in a state like Michigan, a loser can actually sue to recover his losses - although suing the mob was not commonly done!)

If a casino is not licensed to offer dice games yet they offer craps, it is an illegal game. Likewise, if they are licensed to offer poker but they use a pinochle deck (contrary to the rules of the game), it's not really the type of game they were licensed to conduct. If they offer roulette with knowledge that the wheel is defective and out of balance, they are not running a lawful game.

If there are rules about shuffling of decks, I can see how regulators would find that the game was conducted improperly (unlawfully) and penalize the casino. The ultimate consequence of such a finding is that the winners are not entitled to their winnings from an unlawful game.