The Nevada casinos probably handle more currency received directly from the public than most any other retail business. Since they don't examine currency AT ALL at the time they take it in, I suggest the anti-counterfeiting measures are irrelevant to them. As JimK pointed out, they may detect them later hours or days after receipt but too late to prevent a loss. They may get them out of circulation, but they still eat the loss and the counterfeiter makes a profit.

This assumes they are infrequent small transactions. I have no doubt that if you passed $100,000 in counterfeit currency, the casino would be looking at security tapes and the Secret Service would come looking for you [g].