I rarely go on messenger. Well, rarelier than I used to. I'll say away if it's 10 mins or so, or I'll try to be as honest as possible with the Busy etc stuff. But mine just logs me off anyway if I'm gone to long.

I hate people who stop talking to you randomly during a conversation. I also don't like it when people just ignore your "Hi"s. That's just rude. I at least say something like "Hey, I'm gonna be off in a min." And if I just don't want to talk to them for now I'll say that and block them.