I worked for a not-so-short time in a run-down bar... I had drinkers, fighters, junkies and stoners. Guess which group I never had problems with? Yup, the stoners. They were just sitting there, smoking outside and not being aggressive. The drunks would always fight sooner or later.
Feels like your story is incomplete: tell us how did the junkies behave?
edit: oh, forgot the occurence of a junkie shitting into the pissoir. God, what a smell, it was horrid to clean up that mess. And a suspected mentally ill dude smeared feces over the wall.
The gambling addicts were mostly harmless but I had to kick out a couple of them because they tried to sell stolen gear to other customers for cash to gamble.