I posted a screenshot a while back...can't remember if it was in the mob only or in general discussion.
Most people refer to it as a wallhack, but what it actually is is chameleon skins.
Basically, all players show up in a bright neon colour (eg red for axis and blue for allied) and you can see this through walls.
AND...
Whenever a targetable part of the body is exposed it turns a different colour (eg yellow) so you know where to aim to hit them.
I can't imagine the game being enjoyable to anyone when you know exactly where everyone is, but going by the number of people I've banned lately obviously lots do enjoy it