[quote=@DeathstrokeSW]
Because, y'know...the batcave has a shit ton of actual bats. I often wonder how Bruce solved the problem of bats crapping on them...and the billion dollar batcomputer...and forensic lab...
[/quote]

There must be some sort of canopy... that is never drawn or shown in the movies. Criminals aren't really afraid of Batman, they just can't stand the smell of him.