In the case of the like-minded friends of Hitler, they would have genuinely agreed that he was a good person but, guess what, he was a mad man. Of course, Hitler's friends are a case of being A) just like the controversial person. I'm not talking about the people who were too afraid to say a single word against Hitler in order to save their life ( a better case for "B") or young Germans that were brainwashed into believing his lies ("C"). If you really want to know if someone is genuinely a good person see how they treat people who disagree with them. In Hitler's case, he killed those who disagreed with him.
How do you treat others that disagree with you? Do you kill them with your words? God commands Christians in his word to be patient and gentle to those who disagree with them and to try to live peacefully with all men as much as possible (2 Tim 2:24-25; Rom 12:18). The bottom line is that God wants Christians to win people not arguments or self-righteousness. It doesn't matter if the person is your enemy, Christians are to "...Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;" According to Jesus, loving your enemies will bring you closer to perfection (Matt 5:43-48). I would say being close to perfection would make you a pretty good person!
I hope this note was insightful and encouraging. Take a look at yourself to see how you treat others that disagree with you. If those who disagree with you quickly become your enemies maybe it is because you need the power of God in your life through Jesus Christ which only comes by repenting of your sins and trusting him as your Lord and risen Savior. Also, closely examine those who you think have some goodness in them because they are kind to you by seeing how they treat others that disagree with them. There might not be as much goodness as you think.