T-shirt network

In the ad-funded house idea somebody noted that people voluntary walk around with t-shirts with brand names on them. There is a different take on t-shirts with ads on them... Recently Dutch advertising agency KesselsKramer did a stunt for a low budget Dutch movie called Total Loss. A few weeks before the movie premiered they distributed free 'Total Loss' t-shirts amongst all hip bartenders and waiters in Amsterdam. The whole city was wondering what this Total Loss was about. When the movie came out the riddle was solved. It didn't effect the number of visitors to that movie much by the way, it was not that good.

Along this line I had the idea to start a network of waiters and bartenders and other people who work in public places and make them wear t-shirts with ads. They already earn very little, so with the t-shirts they can boost their income with some additional revenue. They also get some information about the product in case somebody asks them about the advertised brand. But how to verify that they are actually wearing today's t-shirt? They should get some incentive to wear it. Provoking comments is not enough motivation for everybody I think.