"De-pr0nify"?! Why on earth would you want to do that...?
Seriously, however, I've never used such a program. I assume they have a list of keywords they scan for, and maybe give you a list of all the "questionable" media files it finds, but are they any help if someone renamed the extensions? (i.e. from .mpg to .bak)
If I seriously wanted to hide pr0n from someone, I'd put in an extra drive or make a separate partition, and instruct Windows (or linux) to not mount that partition on boot.