In any case, I also wouldn't unfriend but would hide (which doesn't seem to be an option anymore) posts from those it was a mistake to friend.
I had two friends who were more work friends than "lets hang out and get loaded" friends. Both of them are republicans and Romney supporters. Being the opposite, I would respond to what I felt was bullshit strongly. I realized that they felt I was coming on too strong and toned back my posts and responses in the interest of keeping the friendship. However, one of them was full on birther and was constantly posting "Obummer" crap. I really was torn about what to do and was looking at the old option to just hide posts when I realized that the other person no longer showed up on my friend list.
Wow, thanks Facebook for the ability to do non-confrontational unfriends.
Bottom line - I just don't want to deal with people who aren't family with whacka-a-doodle/hateful opinions in my life.