20. You Will Be Judged On How You Treat Your Waiter/Cashier
You can tell a lot about a person by the way that they treat others and for some reason, retail workers don't rank very high in the hierarchy of important jobs, which must mean that they don't deserve to be treated with respect. Chances are, if you're rude to someone else who works in retail, there's no reason why you wouldn't be rude to the person you're dating if you didn't know them and were being served by them. Manners literally cost nothing.