I primarily use it to promote, so I will friend anyone and everyone. If someone posts a lot of things that annoy me, I will usually take them out of my newsfeed. Sometimes, I realize that I just plain DON'T LIKE someone, and then I will just de-friend them. If I don't like them that much, I block them to, and POW! They no longer exist.
Sometimes I wish real life was more like facebook.
This. Except I don't "unfriend" or block anyone. I can't be bothered. Just because "friend" is the label facebook uses to designate the people you've collected in your profile, doesn't make it so. The interwebs don't know everything, y'know.

And - God help me - every time I clicked on to FB, there were more of them