Whyizzit that the people you least want to come to your party are amongst the first and most enthusiastic to respond, and they always show up?
You know what I'm talking about. You're planning a party and start with the invitation list. Inviting your friends is easy. Inviting people you feel obligated to invite is done with trepidation. You've invited A, so you have to invite B. If A and B are invited, then C and D should probably be invited, too. If you don't invite E, then the next time you see them, they will ask you (in front of a group), "Why didn't you invite me to your party this year?" Then there is that really annoying coworker. But, since you've invited all your other coworkers (whom you like), then you are stuck inviting Annoying Coworker, too. There are also Weird Neighbors, whom it's easier to include in the party than deal with noise/parking complaints. Oh, and don't forget that person you invited last year because you felt obligated to. Every time they see you afterward, they say, "I had such a great time at your party! I can't wait for next year!" Shit. Then you are stuck inviting them again, too.
However, just because a person was invited once does not mean they will be invited again. Did you bring your bitchy sister who spilled red wine on the carpet and ignored it? Do you treat people like crap but think you're great? Do you think drunk driving is okay? You are SO not invited!
Thankfully, we have a really great group of friends. They make it a lot easier to deal with The Others. They are nice to The Others, too. Despite my griping, the annual party is always fun. I think the trick is to invite lots of people, so dealing with The Others is kept to a minimum.