When you have an emotional reaction to what you see, you are judging. That is your signal that you have an issue inside of yourself - with yourself - not with the other person. If you react to evil, look inside yourself for the very thing that so agitates you, and you will find it. If it were not there, you will simply discern, act appropriately, and move on.
Soul to Soul: Communications from the Heart (ed. Simon and Schuster, 2007) - ISBN: 9781416571483