Shocking conversations...

I'll just listen first and when there is an opportunity, I'll interrupt and tell them that I am not agreeing with the conversation. Just be professional, if you'll listen and be quiet from the start, most probably when you speak they will listen to you. I'm always quiet when there is a conversation going on. So the moment I opened my mouth and speak everybody listen.

You interrupt the conversation and say affirmatively that you do not like the way the conversation is going.You can show your anger and dismay through facial gestures.You can say politely and assertively that the conversation is against good taste.You could then state your views on the matter and if even that is not well understood walk out of that bad situation.