Hmm... I have a friend who has incredible accuracy with real firearms and with the mouse. I'm just glad I'm his friend
God save us all if he ever goes into a murderous rage, though.
Me? Eh... well, I'm not that great at FPS games, but I have been known to accidentally shoot a friendly once, and then that muscle-memory type thing kicks in. I don't think I've ever been fully unconcious of the fact that there are also friendliest in the field, though. Gotta have all the variables running through your mind at once if you really want to be good.