contextualizing the Gospel or moral decadence

I'm beginning to hear more and more Christian pastors using four-letter words. I'm not sure what to make of this. Part of me sees this as an issue of conscience. I think, "If it doesn't offend anybody, then it's helpful in contextualizing the gospel in such a way that others can feel its relevancy." Basically, it removes the barriers that seem to keep "sinners" from church.

But I don't use this language. Why? I believe our culture still views these words as filthy language, inappropriate for a saint. Wayne Grudem wrote an email to John Piper about this very issue. Apparently, Piper used an "inappropriate" word in an breakout session at Passion07. (Piper later posted a message on his website explaining why he regrets using such a word.) Grudem's argument is similar to my gut instinct. Our language reflects the God we represent. How would our immediate audience view this word?

John MacArthur wrote an article on this topic too!

What do you think? Is it appropriate to use "foul" language? If so, which words are appropriate? Also, when is it appropriate to use this language?