Being a bartender for 6 years and a guy who enjoys a good drink now and then I find this to be the dumbest crap ever.
Mostly the bartender is looking for tips. Why would he cheat customers and hurt his chance at a good tip while loosing the chance for customers to return? And if a boss is that cheap they cannot be doing all that well with the biz.
Any the gin on the rim thing, WTF? Sorry that is just too dumb.