"People need to realize that proponents of bad ideas can teach us things, perhaps unintentionally."
As soon as I read that, the first thing I thought of was Mein Kampf. My junior high American Lit teacher (same one who gave us Huck Finn, now that I think about it) had a copy of Mein Kampf and some of the other students gave him some shit about it. He explained to their tiny little minds that he wasn't reading it to learn how to become the next Hitler, but to better understand the guy's ideas, which were not all bad. Nobody, good or evil, rises to that level of power without smarts and skills.
This was the same teacher who talked about Kansas and Jethro Tull (this was in the 70's) and he played Funkadelic's "Maggot Brain" for us one day in class. Brilliant, open-minded guy and great teacher.