You make a valid point - However if the word is unknown to you could you find it offensive? I am not sure what people would think of this.
I think that dws's suggestion about a proxy here at Re: Profanity in the monastery would suite best and one would have to manage a list of words they found offensive in their own proxy.
Update: Not every newbie has the ability to find and customise a proxy written in perl to perform this filtering for them.. hence the idea which in retrospect is probably not feasible to maintain centerally any way.
Of all the things I've lost in my life, its my mind I miss the most.