You should definitely get rid of whatever is being used currently. The first group I randomly clicked (alt.alien.visitors) was censoring the word "public" (and "sucks" and "pipe"), multiple times in the same post which, if it happens a lot, especially on innocuous words, is really going to spoil what is an excellent project.

Its not a bad idea to filter content though, and/or have a flag button on threads/posts. 300 million articles from 40 years of an obscure and anarchic corner of the internet are bound to contain posts that are either potentially illegal or which you otherwise don't necessarily want to be publishing.