How do you implement a good profanity filter?

Question

Many of us need to deal with user input, search queries, and situations where the input text can potentially contain profanity or undesirable language. Oftentimes this needs

Answer 1

Frankly, I'd let them get the "trick the system" words out and ban them instead, which is just me. But it also makes the programming simpler.

What I'd do is implement a regex filter like so: /[\s]dooby (doo?)[\s]/i or it the word is prefixed on others, /[\s]doob(er|ed|est)[\s]/. These would prevent filtering words like assuaged, which is perfectly valid, but would also require knowledge of the other variants and updating the actual filter if you learn a new one. Obviously these are all examples, but you'd have to decide how to do it yourself.

I'm not about to type out all the words I know, not when I don't actually want to know them.