פירוש על עבודה זרה 36:9

Meir prohibits going to a theater or circus because idolaters offer sacrifices there. We should note that the Hebrew states, “spread manure,” but clearly this is a malephemism (opposite of euphemism) for offering sacrifices. The other rabbis offer two reasons why one should not go to a circus—if sacrifices are being offered there, then they will be suspected of offering sacrifices. If they are not offering sacrifices, then it still is forbidden because it is participating in a “gathering of the scornful.”
However, the Talmud notes that there is a difference between the two reasons. If sacrifices are not being offered and he engages in business there, then the proceeds of his business are not prohibited.