In single deck hand held blackjack then there is a cheating move that dealers can employ where the player is permanently playing against a negative expectation deck. The average edge that the casino has over a player is derived at by combining all of the positive situations and the negative ones and then arriving at a sum total.
But in the event that a cheating dealer can card count and is prepared to shuffle the cards every time that the deck goes positive for the player then they are increasing the house edge against them.
Let me explain a little better, let us say that the running count is -5, this means that the remaining cards are lower than average and have fewer tens and aces. This is an advantage for the casino and in shoe games then this makes no difference. But in hand held blackjack where the dealer has the option to shuffle whenever they want then the dealer can simply deal out some more cards knowing that the player is under a disadvantage.
But if the running count was +5 then the dealer could shuffle the cards. This means that the player would be playing under an almost permanent disadvantage and probably losing many more dollars per hour. A player who was betting $50 per hand and playing 100 hands per hour would be placing $5000 per hour in action.
If a dealer was preferential shuffling and achieving an edge of around 2% on average then this player could be losing around $100/hour. Many dealers who are chasing tips would prefer that this went the other way as they would rather players won than lost if a large part of their salary was dependent on tips.
