What do you think about adding profanity suppression to Aspell as an auxiliary file? By adding an additional file of profanity, we can make Aspell recognize correctly spelled profanity and not flag it, while avoiding giving profanity in the suggestion list. I consider this ideal in that it doesn't get in the way of somebody who wants to use profanity, but it avoids pushing it in somebody else's face.
It would allow sites to customize the level of suppression to match local sensibilities without risky direct modification of the word list.
The big downside is the complexity. We would also not help correct true spelling errors in profanity, but if you're using profanity anyhow, then the formality level of your writing is so low that spelling errors are accepted and even encourgaged.