This exploit right here is like pretty much used by everyone or used so much that it makes it seem like its a in-game thing, something that's there on purpose(but its not). Basically its just looking through walls/structures to spot people inside of buildings or outside of buildings and so on.
- Legacy ID
Steps To Reproduce
Just look up with you gun pointing up with your back touching to wall and using the ALT KEY to navigate around.
This bug/glitch/exploit or whatever has been around for a while.