What can be done about fake monks?

in the city where i live (Toronto, although this is an issue in many cities around the world), there are people dressed as monks soliciting others on the street for donations. In return, various good luck charms are offered. The fake monks speak little English, and will try to justify their begging with the claim that donations are for building a temple back home. Is there anything I can or should do about this? Are these fake monks giving Buddhism a bad name, or at least obscuring Buddhism's true message? Are the fake monks doing an ironic good by giving people the chance to practice generosity?