I've spent 30 years in the 'night time economy', to varying degrees, and you get a good understanding of human behavior being immersed in it.

What I've found interesting is that the alcohol/drugged up individual, while out of their heads, is not a 'different person' much,  to when they're  in a sober state. 
They just hide who they are easier, when sober.
They  express themselves 'more' when inebriated. (in good ways and bad).

Living the night life  certainly gives you a radar for those best to give a wide berth to.
Knuckle draggers cannot be reasoned with.