Some of the things he said are true regardless of his deeds...and you have to admit he was an AWESOME speaker.
Well, you'd have to be specific about the "truths" that came out of him. I have listened to his speeches, and yes, he is innately capable of drawing emotion from his crowd to fuel his words. But if you listen carefully to what he is saying, you realize there is almost no content in his speech: what he says in 20 minutes can be summarized in 2. I suppose it is in his best interests to keep the speeches content free, as his points really had little logical basis, and he wasn't going to be able to manipulate his audience with reason.
(re: original point) : yes, judge a quotation by what is says, not who said it. On the other hand, if a friend of mine started writing down Hitler quotations all the time, I'd think that would be more disturbing than if he had been writing down, say, Orwell or Shakespeare quotes; while a quote on its own should be judged by content, if you are pushing out the works of Hitler, that suggests that you idolize the man, which is your right, but is not an image an institution would want to have.
Watch Pierre Trudeau, (in my opinion one of the greatest speakers ever), completely dominate this reporter who was looking to demonize him. It's brilliant how he turns things around.
http://archives.cbc.ca/IDC-1-71-162-429-21/unforgettable_moments/conflict_war/trudeau_just_watch_me