The Kefauver committee found that it was widespread. There were indictments in the early 1960s of casino owners for tax evasion. Skimming can also occur with the granting of credit. Credit can be granted to individuals who aren't required to repay all of the loan. One solution is to prohibit credit, but that can increase the problem of loan sharking.
Money laundering is another problem.
Bettors can come in with a large amount of cash and purchase chips. In California cardrooms, where the house is not the banker, it is harder to dispute claims of large winnings. Employees have to be alert to the time periods and possibility of multiple transactions. Another issue is kickbacks. These occur in a variety of different situations.