So, here's a thought experiment: consider "Carl H". Carl H ran the site computerscienceforeveryone.com. He was an incredibly passionate individual who spent his time creating free video tutorials on C programming. Along with these videos, he created supplementary materials, quizzes, and engaged with anyone who had questions. He even provided live one-on-one instruction to people over Skype, all for free. By all accounts, he was an excellent Computer Science teacher.

Carl was arrested for molesting his nine year-old son. He committed suicide in jail awaiting trial.

With that said, do we disregard all of the learning materials he created? Is their value inherently reduced to zero now that we know they were the product of a sick individual?

This isn't just an thought exercise. Carl was a real person. He had a Reddit board dedicated to his lessons and instructing people. His website has since lost its host and pretty much all the videos are gone from the web, save for p2p torrenting, because no one will be caught dead hosting videos from a child molestor, not matter how innocuous the videos themselves were.