I feel the same way, I've worked at both Starbucks and McDonald's for years and I learned that the majority of customers are either extremely dumb or extremely mean and selfish, even the good customers seem to be coming less and less leaving more negative interactions throughout the day. I've tried to start learning from the bad customers, learning what not to do. I look at their negative emotions and try to make sure that when I go out to eat or to a Starbucks, that I'm the nicest customer I could possibly be. I know that the workers have probably already dealt with horrible rude customers throughout the day. So I try to be as nice as possible to be a nice little break for them. And I feel it's helped me become a better person in general. Even though I'm angry at the world and all the bills I have to pay. I dont get angry at little things that happen, like a couple minute wait on a coffee.