Not had much trouble in 13ish years of gigging. Last time was while setting up in our local services club. The doorman came over and started shouting about how we're about "three octaves too loud" then threatened to break my then brand new guitar. I was fucking livid but managed to keep reasonably calm. He was pretty old, clearly not in great health and bloody lucky we're not the sort to kick off. If it had been my previous band, the singer and drummer would have probably killed him! :D I always hated that place, full of total wankers and thankfully won't be playing there again.
I remember gigging a bikers pub in the late eighties, we were about 18 at the time. They hated our original hair metal material and offered some inspiring comments during the break, such as "you go back on stage and I'm gonna shove that guitar up your arse" :)
These days it's the job of the venue to keep things smooth as it's their money. It's roughly £200 an hour, do you want us to play music or argue with a pissed up loon ..... cos it's £200 an hour either way :)
We're pretty lucky in that two of us are 6'3" and our singer is a Wookie.. our bass player is smaller but he's Glaswegian. We still get the "clever" comments, but no aggro.
Our worst venue for fighting and drunken door blockage was in Cheadle Staffs. Mid set we could see stools, tables and glasses flying around (just out of view). As above nobody batted an eyelid except us. We've never gone back, but my co guitarist wants to for some reason.
You should try being a soundman threats all the time and thats just from the band:)
We played a wedding this year where a large chunk of the audience were fucked up on something other than alcohol. In a break, we were walking back to the venue when out of nowhere, a guy attacked our singer from behind,throwing him to the ground.he walked off immediately and on confronting him, he was incoherent saying he was worth a million of us. I told the groom we were one whisker from leaving, he was mortified as it turned out this was his brother! We carried on but only because the bride and groom were very decent people let down by cunty pikey relations.