They Google every recipe on their phone
If you don’t know how to make an Old Fashioned, you should at least have a dusty, 100-year-old, leather-bound book laying around for reference.
They ask you how to make drinks
Sure, more complex drinks might provide a challenge, especially if they have weird regional names. But if you don't know how to make a whiskey ginger… maybe a new line of work is in order.
They use sour mix for any citrus drink
It's like using Pledge in place of lemon zest.
They're constantly trying to hook up with customers
As a fellow human, I understand the primal urge to procreate. As someone who's been waiting on a Modelo for 15 minutes while the barkeep chats up a woman in yoga pants, I hope they never get the chance to procreate.
They treat servers like trash
This might be more jerky than bullshitty, but still: Any bartender worth their salt knows a restaurant is a delicate ecosystem, and treating co-employees poorly is the quickest way to sabotage your career. And the bar.