Dealers are getting more and more brazen about this. I've been to casinos where the dealer has a trap door like device to his left. During the hand, he'll move chips over there, and after the hand, when everyone is waiting for the next hand, he'll drop the unsuspecting chips into an unknown dark place.
They are very sophisticated about this, they've figured down to a percentage/maximum how much they can steal without players noticing or complaining. At some casinos, they reserve 2$ or 3$ chips just for this theft. Hell, sometimes the floors come over to move their stolen chips away for them!
-- sorry couldn't resist.