Missing an assailent isnt always a total fail. I'd bet that more often even a miss will cause the desired effect from the assailent. I doubt if there is much information regarding the actions of a person once they have been shot at.
Probably very true. I heard someone say once (Massad Ayoob perhaps?) that a person could get 90% of the benefit of a concealed carry handgun by just carrying a pistol loaded with blanks. The majority of the time, just displaying the weapon ends the situation. If you do need to fire, they won't know you are shooting blanks, all they know is that they are getting shot at, and most of the time they will run. The guy who said it was not advocating carrying blanks, but his point was that the vast majority of successful armed self defense situation end without any blood being spilled.