just because the bible doesn't address them directly word for word, doesn't mean they are right to say. Think of this way, words are only that right? Just words. No, they aren't just words. We use them to communicate ideas to one another. What's communicated when someone says poop is different than what's communicated when someone says sh**. It's just like the word gay. It used to mean happy, but we started using it to mean something else. Now when someone says gay, you know they are mentioning homosexuality, or that something is "stupid". It's the same way with a**. It once was the name for a donkey, but over time, people started using it as a way to insult people. Now a word that simply meant donkey is used to refer in a negative connotation to one's butt, or to insult someone. Words have a meaning, they also have a connotation with them. They have power because people give them power. Just because someone doesn't know what a word means in another language, doesn't mean they can't figure out it's bad. The way we look, act, and how we inflect when we speak all give the feeling that we've said something insulting or "bad". I can usually tell when someone who is speaking a foriegn language has used a "naughty" word. God knew we were going to have naughty words that our societies have deemed impolite (and they are usually words describing some disgusting, sinful, hurtful, or obscene thing anyway), and that those words would change. That's probably why he didn't have them listed word for word in the Bible.
Let's face it, we use bad words when we are angry, when we want to be obscene, or when we want to hurt people. Bad words are RARELY used for anything but that, and I've NEVER heard them used positively or for the Glory of God. So why use them at all?