Q: “How do blackjack dealers identify card counters and what do they do if they think someone is counting cards?”
A: There are many things the Dealer looks for when spotting a card counter. A few of these things include looking for Players who bet large and small amounts sporadically. For example, if a Player bets $10 on the 1st hand, $200 on the next hand and then they go back down to $25 on the 3rd hand. Another thing the Dealer looks for, is if the Player is extremely focused on all of the cards and they’re not drinking, not talking and basically just not having a good time. The Dealer will also notice if the Player is following the book or not.
Now a lot of people don’t realize this, but there are Dealers who can count cards as well and a card counter can typically spot another card counter. These Dealers are usually counting their own cards 8 hours a day; 5 days a week plus they have experience dealing to other card counters. Because of this they are more knowledgeable than the typical card counter and therefore they can easily spot when someone is counting cards.
Other times the Player is extremely obvious or just really stupid. Stupid enough to tell the Dealer that they’re counting cards. Or, if the Player is on a single or double deck, they’ll straight up ask the other Players if they can see their cards.
I want to stress that card counting is not illegal, casinos just frown upon it. Usually they’ll give you warnings and if you don’t stop then they’ll throw you out. This is also known as being 86ed. In the most extreme case, the casinos could have you arrested for trespassing since they are private property.