Get Real by Donald Westlake

John Dortmunder and his friends are hired, against their better judgement, to do a reality show about a gang of crooks who meet at their favorite bar in the back room.  Only they really want to rob the building where the filming is taking place in a mock-up of their favorite bar.  The real target is on the floor below the filming.  But it appears that it is used infrequently by visitors from out of the country.  When the gang breaks-in to find out where the real money is hidden, they discover that the real crooks are the people that own the company filming the show.  The gang doesn’t take all of the money, but the company isn’t going to go to the cops, because then they’d have to admit that they’re skimming the budgets of the shows they’re making and sending the money overseas.  All they can do is cancel the show.