Today, I was walking home when a man stopped me on the street and asked me where he could catch a bus going uptown. I directed him to a stop half a block down and told him that if he just kept walking, he'd hit it. Frustrated by the fact that he would have to continue walking, he let out a bad word.
I was bothered by this on many levels. An adult using a bad word while in conversation with a young person (especially one he or she is unfamiliar with) is just inappropriate, and makes for a poor example. I know that cursing has many negative effects, but a lot of people in my generation don't. Other teenagers may think (probably more on a subconscious level) "Well, if this man curses and he's an adult, then I can curse too!" Luckily, I know otherwise, but this man didn't know that when he used a bad word.
It's also just not appropriate for a someone to curse in front of a stranger. Just because I know what the words are doesn't mean I want to hear them!