The popularity of credit card deposits has given crooked gamblers some tools to scam casino sites. There are reports of gamblers who deposit money to a site, gamble, lose, and finally claim that the first deposit never went through. In such a case, the bank may issue a full refund resulting in losses for the casino. However, in this day and age, casinos have created a shared black book for untrustworthy clients. The black book is shared among different casinos if these people hit other online casinos on their deceitful venture.