Jonah Lehrer writes for Wired about a statistician who noticed a pattern in the visible numbers printed on scratch-off lotto tickets, and from that was able to figure out how to tell if a ticket was a winner without scratching off a single number:
I then ask Srivastava how a criminal organization might plunder the lottery. He lays out a surprisingly practical plan for what he would do: “At first glance, the whole problem with plundering is one of scale,” he says. “I probably couldn’t sort enough tickets while standing at the counter of the mini-mart. So I’d probably want to invent some sort of scanning device that could quickly sort the tickets for me.” Of course, Srivastava might look a little suspicious if he started bringing a scanner and his laptop into corner stores. But that may not be an insurmountable problem. “Lots of people buy lottery tickets in bulk to give away as prizes for contests,” he says. He asked several Toronto retailers if they would object to him buying tickets and then exchanging the unused, unscratched tickets. “Everybody said that would be totally fine. Nobody was even a tiny bit suspicious,” he says.
It's suspected that through exploiting holes like this in these scratch-off games, criminal organizations are using the lotto to launder money.