This isn't a bug as much as just an inconvenience.
I brought this up a long time ago, but coming back and playing now it's still super annoying.
What the problem is: You can hear peoples footsteps from across the map as if they were standing next to you.
For instance, load up shazam22 and have a friend on the other team; when you spawn one of you run around and the other just listen. You can honestly hear them pick up guns, barrels, paint grenades etc. as if they were in your base. You can actually tell which route someone might take based on this information.
I have a theory that this happens in .BSP when the map creator mirrors the map, but I know nothing about .BSP so I am most likely wrong.
doubt there is an easy fix, especially since you would most likely have to tweak each map individually, but a fix nonetheless would be awesome.