I was once peripherally involved with a local volunteer fire department. (Had a friend who volunteered, and I was around pretty often.) They were some of the most sexist, racist people I've ever met. But when they were down drinking in the basement, and talking about the "hot sluts" they saw that day while on duty, no one ever said anything. (Other than to talk about which one they would 'do.') So as far as they were concerned, they weren't being sexist. And the (few) women there knew to keep their mouths shut lest they be labeled "stuck up" and excluded from that very insular community.