Except that according to Bringing Down the House, they had been told not to come back to some of the casinos, and were using disguises to avoid being thrown out again. They were tresspassing, which is a criminal act.No, it's really no more of a scam or criminal act than, say, encrypting your email. There's nothing wrong with obscuring what you're doing.
But I agree that team blackjack play can't be considered a scam, especially the part about having spotters waiting for a hot deck. If the casino offers a game where the player has the advantage, a savvy player will take advantage of that. The casino can always change the rules of the game, or choose not to offer it.