Is it obligatory to denounce evil in places where sins are committed, such as barbershops that display signs indicating the shaving of beards, even if the act of shaving is not actually taking place? And is it sufficient to advise the workers without denouncing the owners of the shop?

Shaving the beard is forbidden according to the majority of scholars, and announcing its shaving in the shop is a reprehensible act that must be denounced as a collective obligation (fard kifa'i). As for the expected reprehensible act (such as directly shaving the beard), there is no denunciation against the workers for it; rather, only admonition is prescribed in this case.