On a sidenote, I don't see why people get so annoyed when you say you're too busy to talk when you're not on away. So you messaged them and they were busy. Who cares? It's not like they're going out of their way to annoy you, and if you're that easily annoyed then it's your own damned fault.

"Heya." They message me.
"Hey man." I try to make an effort to always just leave it at 'hi' to see if they're just going to ask a quick question or if they're actually wanting to chat about anything.
"How are you?" Ah, so it's the latter.
"A bit busy right now. Why, what's up?" Just double checking to make sure they're actually wanting to babble and weren't going to follow it up with a quick question.
"Ah, nothing much. I'll catch you later." So it's not just a quick question and they're looking for the entertainment that I don't have time to give. Time to dismiss.
"Yeah, sorry. Have a good one, though, maybe I'll chat to you later." Maybe!

There are probably a lot of EoFFers that have had conversations with me that have gone quite similar to the above.