I also feel like a magnet for this! I ended a relationship with someone who did this to me after trying to work around it for years. If I tried to say something, she'd talk more loudly! I tried scheduling things to do that wouldn't involve me listening to her, but she'd always find some excuse to change our plans.

With other friends, I limit the amount of time I spend with them. I have found that with one friend, if I can keep him off certain topics, he doesn't do this. Once he starts going down that road, I leave. I've also just walked away, like Christina mentioned. I am not sure they always notice...