It's hard to be around grumpy people. We seem to take their bad mood very personally, as if we caused it. "What a creep that person was! He pushed past me as if he didn't even see me!"
Maybe he didn't. Maybe what looks like someone with a poor atttitude is a man who just learned his beloved wife is dying of cancer. Maybe he just lost his job or his home. Maybe his child is failing in school. We can't know what makes a person look so unhappy. Instead of meeting rudeness with rudeness, maybe we need to take a deep breath and smile. You'll feel better and who knows? You might be that one bright spot in someone's day.