You can tell a lot about a man's character by how he treats the people around him. This is especially true when you witness a man's behavior toward those who are in less powerful positions, like food servers.
When you're first getting to know a potential romantic interest, he will probably be on his best behavior with you, but he usually won't be out to impress the food server. Notice his interactions with the staff. Is he polite and friendly? Is he demanding and entitled? Is he rude and callous?
In addition to food servers, notice your date's interactions with the cashier at Target, the barista at Starbucks, and with anybody else in a service-type job.
And, don't put up with bad behavior! If your date can't be polite, find a date who can. If he's are a jerk to a stranger, it won't be long before he is a jerk with you.
I'm a gay father with gay sons. My mission is to work with the community to prepare them -- and other young gay men -- for a happy and successful life.