The other night at the poker table, one of the players was telling the guy sitting next to me about all the freebies she'd received in the mail from the casino. They'd sent her coupons for free meals, free hotel rooms, etc. He said she must play the slot machines a lot. She confirmed that she did, and had been having a lot of luck recently at the slot machines in the high-roller room, winning a few big jackpots -- $12,000 and $19,000 and $50,000.
Surprised by her good fortune, he asked if she used her player's card in the machine. That's a card that players can use to earn those freebies, called "comps," from the casino. This process is not unlike the early stages of dating. The more time and money you invest, the more you're going to be loved. That doesn't mean you're going to win, but the casino is going to encourage you to keep coming back and playing, and those freebies are the enticement.
Using a player's card is simple. When you sit down at the slots, you insert your card in the machine, and it tracks your play. The same thing goes on at table games like blackjack, craps, and roulette -- you hand your card to the dealer and the floor man enters your information into their computer and notes how much you're betting and how long you're there.
In the poker room, you can swipe in at the table to earn credits, but because you're not playing against the house and the casino doesn't make as much money from you as it does from the slot and table game players, the comps for poker players are much lower. Still, regulars can run up a few free lunches or dinners each month. All of this is voluntary, a system you may opt into, but if you prefer to play anonymously, no one's going to force you to even get a card in the first place.
When the winning woman confirmed that she did put her card into the machines, the guy next to me said something like, "I bet you won't keep winning, because they know how much you've won already and they don't want to keep paying you off."
Like most conspiracy-theory arguments, this one has no basis in logic.
Casinos have no need to rig the machines, because they already have the edge. By law, they have to post signs that tell you the average return on their slot machines. Let's say it's 95%. That means that if you give them $100, they'll give you $95, and they'll make that deal as many times as you want. The reason people are willing to accept that proposition is because of the possibility of winning so much more -- jackpots in the tens of thousands, like this woman did.
In business terms, the casino doesn't care whether you (as an individual) win big. In the long run and over the huge player pool, it has the advantage -- even if it's as little as 1% on some table game bets -- and is going to make money as long as lots of people keep coming in and gambling. It would never do anything to risk that mathematical edge. If any casino were found to have rigged its games to keep specific players from winning (or continuing to win), it would be horrible for business, not to mention the trouble that would rain down from the state gaming commission.
The challenge for all casinos is keeping customers' perception in line with that reality, and keeping them coming through the doors. They don't do that by ripping players off. They do it by offering the opportunity to win and have some fun while trying to do so.
The math does the rest.