Generally low, grips, and long or short triggers, may enter into it also regarding left and right. At any rate jerking the trigger, or flinching will send a bullet somewhere else.
i have seen people almost seem to want to fall down when getting an unexpected click instead of a bang. What is also interesting is I have seen even some pretty good shots do the same thing, sorta, when getting a click instead of a bang. According to the late Jeff Cooper, that might be a post ignition push. He might have been on to something there.
Still yet, the shooters that impress me the most are the ones that remain rock solid after a failure to fire.