A man voices his opinions on economics, public policy and freedom. And when they don't agree, we hear, "He's fat, was mean to Michael J. Fox and was addicted to pain pills!"
Is the idea here that if I can prove the evilness of the man himself, then that proves the inherent wrongness of his ideas? Because Karl Marx was an anti-Semite, and according to some historians, an adulterer.
Does that dismiss socialism as a valid economic concept as well?
If the character of the believer disqualifies the content of the belief, I'm not sure we're left with anything.