so, being an anti-drinking,smoking,drugs guy, and an introvert...bars and clubs are my worst nightmare for this very reason....
all of my playing life, I am the guy who loads in quickly, gets my stuff set up, and then hides in the green room, or some dark corner of the place. I tell freinds who are coming to gigs that I will talk after the set. If there is not a backroom to hide in, I will run the merch spot, and "hide" there. This allows me to avoid most interactions with drunks and wierdo's, or at least lets me cut off those convo's to sell stuff.
playing in punk and metal dives most of my life, there has always been shifty, and downright dangerous characters in the clubs, and I got real good at reading body language/dress/facial features, and proximity things. Being (usually) the only sober one at the end of a show, I also had to sort of be secutiry/babysitter/defense, which REALLLY put me out of my comfort zone. I learned that a very quick and forcefull "NO" OR "WE'RE BUSY" cut off a lot of possible skirmishes; also having a big scary knife helps
this usually really cleared out back alley ways or idiots at load out. Never used it, but had to pull it 3-4 times to make a point....
I have a rally short fuse with drunks, and would tell them to just get the f#$^k away if they were babbling nonsense and real close. I didn't care about burning a bridge or losing a friendship there. I think I was never a "scenester' because of this....

. If you are sober, lets talk!!! If not, I don't care....