I had talked to you about bad music before and this is my opinion (it might not be the right one). I believe that taking God's name in vain is very bad. But I think that slang swear words are not. I do not say any of them but wouldn't you agree that they are just words, and if no one made them up they would not exist?
Slang words for profane words are called euphemisms. See Careful What You Say about why some words are bad and whether euphemisms are wrong. What you are forgetting is that words have meaning. If they didn't, then what comes our of mouths would be just a jumble of sounds. We select certain words because of the meaning they carry, even if we don't always think about meaning in detail. To prove this, instead of using a euphemism for God or Jesus' name, for the next week I want you to say the name of some flower. Tell me if the meaning of the word really doesn't make a difference in what you say.