Free play has become one of the primary ways casinos reward loyal customers who use players club cards. As with complimentary meals, rooms, shows and other perks, the amount of free play you get depends on how much you play while using your card.
But players often wonder if there’s a hidden cost, as in the following email I received from a reader:
“With the new computer/electronics, is there ANY way for the casino to LOWER the payoffs on slot machines, when the computer detects that you are "playing" on the $300 credit, and thereby changes the odds in payoffs? (Perhaps using another set of codes?)”
Such programming would be illegal in licensed casinos, and would be weeded out by the gaming labs before game was ever approved for installation. In games that actually make it onto casino floors, the random number generator doesn't know where the credits on the machine came from. Free play, cash, tickets — it makes no difference to the RNG.
You're getting the same game with free play as with fresh money.
If you tracked results over a very long time, you'd find your payback percentages with free play would be roughly the same as when you use fresh money or when you use tickets brought over from other games. In the short-term, anything can happen, and a bad streak or two or three with free play can lead us to conclude there's something other than random chance at work.
Keep in mind that casinos don’t want to short-change the players they’re trying to turn into long-term, loyal guests. The house has all the edge it needs built into the games, and is willing to reinvest a small portion of its proceeds into building customer loyalty.