Re: Best way to respond to passive aggressive behavior.
Google books on dealing with passive/aggressive people. You can choose to ignore them if you wish, they may or may not stop. The best thing to do is when they act like that is to call them out on it. Acknowledge the fact you know what they are trying to do, tell them you're not playing the game(thats pretty much what it is to them, game playing) do not take what they are doing/saying personally. Realize they have some issues and then go about your business. Don't play their game, its what they want.
"When people are truly sick and tired of being sick and tired, that's when they will make a change."