I have no clue why my Gay friends find it offensive. Honestly, I feel it is out of respect for what they are comfortable with. Perhaps instead of making generalizations for my being PC with my friends I shouldn't speak for a community I am not a member of.
As for me the reason I am senstive about such things is I was just told I was a cheating slut whore,by someone who doesn't know me, but emailed me to let me know. Wanted to have a fling with me and I wasn't attracted to him or his morals He thinks me being poly, is an open invitation. When he is the one hiding his relationships from his wife. So perhaps right now I am a little senstive to labels.