Since pain interrupts shooting, it is a useful tactic to quickly spray bullets back and forth between enemies in a room, keeping them all constantly stunned. They will be unable to shoot you, so you escape major damage, though possibly at the cost of ammunition.
Enemies that experience painEdit
The number of enemies that experience pain make up the majority of enemies BJ will face. Guards, SS, Mutants (and Bats), and Officers each experience pain. Each of them has two sprites that may represent the state, and each Pain state lasts ten tics (or about .14 seconds).
Enemies that do not experience painEdit
While most of enemies that B.J. encounters do feel Pain, the majority of kinds of enemies do not. None of the bosses do, so any boss will continue to shoot right back at you. Ghosts and Fake Hitlers do not experience pain. Dogs do not, but mainly because they only have one hitpoint anyway and immediately die from any attack. Being completely invulnerable, the Pac-Man Ghosts also do not have a pain state.