There’s a breed of professional gambler known as advantage players. They employ perfectly legal methods — counting cards, tracking shuffles, peeking at the hole cards of sloppy dealers, etc. — to extract piles of money from casinos. And even though they’re breaking no laws, casino bosses despise them. Sometimes they treat these advantage players — also known as APs — like cheaters. Security guards handcuff them, not-so-veiled threats are made, their chips are refused. Occasionally the APs will even get thrown in jail.