You could sell filters that expire after x numbers of uses of the word in question, but that’d be open to people getting rid of a filter they don’t like by using the word over and over again.

To do it properly you’d need stats on word frequency in IDC, which I can only imagine being infeasibly costly in terms of computer time to break down and count the words in every IDC message.

Maybe something similar drawing on canned statistics for word frequency… if such statistics exist. But I doubt they’d include all the words that are common around here even if they do exist.