Barbacking is kinda tough. You run alcohol from the back to the front through throngs of drunk people. Then when you get behind the bar, these same drunk people don't understand that you aren't a bartender and will try to place orders with you. You can a) avoid eye contact

act like you're a bartender except you don't pour their drink because you can't or c) point to the real bartender. Whatever option you choose, people get mad because they don't understand that somebody has the job of keeping the bar stocked, and there is no possible way that you're not a bartender.
Plus cleaning puke sucks. And your weekends are shot.