At the end of the day, gambling is global. It doesn't matter what country or what religion, if people want to gamble, there will always be someone willing to run a game.

In Qatar, where casinos are banned, at least 2 gangs have been found running illegal card games. The players are contacted via text message and run in houses of out-of-town unsuspecting owners, where a 'caretaker' is paid. Gambling doesn't discriminate within players either - everyone from private sector businessmen and cab drivers are involved.

The gang makes its money by taking 10% of the winnings. Games begin after midnight and there can be 20-25 people playing.

As for finding those involved in running the games:

The source said gang members were never caught because they change their hideouts regularly and admittance to the circle of their habitual players is very difficult.

Article: Gangs run card gambling dens in Qatar homes