"Who are you? Why did you just invite me to your group? No, I don't want to duel you. Get away from me."
Maybe I'm alone in these thoughts, but I never did understand why somebody would invite me to a group without telling me what the heck they want out of it. Do people assume that just because you are in the same zone that you are doing the same thing (i.e. same quest) as them? Or perhaps the person is so socially depraved that they can't go 5 minutes without forced social interaction.
When this happens I try to be polite and ask what quest they are currently working on. If it's the same as mine then I know it's safe to group...for a while anyway.
When I am done with my quest my brain starts to tingle, my fingers slowly move to my mouse and over my portrait, I right click, open Party chat, then...
Gronthe: Did you get what you need?
X: I need one more
Fight, loot, finish quest.
X: I got it!
Gronthe: Great! Hey thanks, cya
X: Wanna run a dungeon?
Gronthe: Uh, no thanks, I've got other stuff to do
X: Wanna kill stuff?
Gronthe: Gotta log, sorry.
Then I log out. 5 minutes later I log in. Free and clear.
Wow, I am so socially inept, aren't I? I think it's because I hate confrontation, I don't want to tell somebody else to "get lost, noob", that's just rude. But I don't want to "just kill stuff" either. And if I wanted to run a dungeon I would have queued in the LFD and never would have accepted a group because that would have kicked me out of the queue.
I am not a particularly social being, I am incredibly shy in RL and in-game. I don't mind the occaisional group-up to complete quests with others in the same cave as me, that's fun. But usually if I'm questing solo it's because I want to be alone. Anything beyond needing another to down an elite disturbs by state of zen.
But that's just me, I'm simple that way. I bring my personality directly to my characters (to the extent that's possible). When I feel sociable, I talk, when I want to be left alone, I quest. For me my playtime is serious business, in that I want to have fun my way when I want it. The random group invite simply messes with my mood, especially when it comes out of nowhere with no explanation.