Good vs Evil- on wobble(board)y ground

The Rolf Harris trial has had a lot of media coverage, with many vehemently defending his "innocence" right up until he was convicted, and even some beyond.

For most of the people defending Rolf, they will have had little or no personal contact or knowledge of his actual personality, behaviour or traits- most will never have been to a concert, let alone had a conversation with the man. As Amanda Harris writes, many should forgive their own guilt of being a fan of Rolf's, and focus on those memories having been formed in innocence- without knowledge of his behaviour beyond performing (http://theconversation.com/dealing-with-the-happy-memories-of-a-disgraced-rolf-harris-28722)

The motivation to protect his reputation, honour or dignity is really an attempt to protect their own levels of comfort with having idolised someone who was capable of such deeds. I am most interested in how far some people pursue it though; even where there is clear and obvious detriment to others, ie the women and children he abused. Is it that the need to hold on to a positive sense of self by not believing you supported someone "bad" or "evil" is stronger and more important to them than the wellbeing of others and the protection of potential future victims? 

Certainly we place a lot of trust in public figures and celebrities, and the feeling of being let down can lead to some highly polarising attitudes. Recently a friend posted on social media that she believed Al Gore was a hypocrite because he travelled in a private jet while posing as an environmental hero, spruiking climate change and the need for people/ businesses to reduce carbon emissions. I was surprised at how direct the criticism was and that a single negatively perceived action could potentially override any or all positive actions and/or have a dramatic influence on a person's opinion of someone. Perhaps it is because there was not a great personal association with Gore, as there was for many with Harris- intense positive emotions of childhood vs knowledge of someone in a political context from adulthood?

Logically, the more inconsistent the behaviour with how a person promotes themselves, the more surprising it will be in relation to our psychological concept or beliefs around who they are- a single man who has multiple sexual partners is not surprising, questioned or criticised unless he is a priest- one who has promoted themselves as not supporting such actions. 

Does that necessarily make the priest a "bad" person though? What about a medical practitioner who is also a smoker, or obese- are they hypocrites? I would be less likely to take the advice from someone who was unwilling or unable to demonstrate that they will not heed their own advice on those direct issues, but I wouldn't discard the entirety of their professional abilities. 

Growing up I had a lot of internal conflict. I was told endlessly that you should love your parents, respect them and not "betray" them by saying negative things, although there was much physical violence and psychological abuse directed towards me. I felt guilt that I was a "bad" child to them, and that society's perception of them as "good" people was more important than my physical and emotional wellbeing. There was also the desire to not be discriminated against or socially outcast by anyone who found out or suspected anything was unusual with our family. At times, when things were particularly bad, and I attempted to tell someone, they'd usually reinforce the situation with "but your father is a good man- he's a doctor!". 

A medical specialist, yes. Good
An intensely controlling, violent and abusive father and partner, yes. Bad 
A member of the P&C committee at the school, volunteering his time, yes. Good
Someone who would threaten to kill your siblings if you ever told anyone he had kicked you for spilling some milk, yes. Completely fucking evil.

Why can these actions not necessarily co-exist in people's concepts of what a person "is", and why do people have such simplistic notions of "good" or "bad", rather than accepting that humans and their behaviour are multidimensional? 

So long as these concepts are upheld, many barriers to victims coming forward and being believed, being able to press charges, and to not be doubted and ashamed for challenging those who others respected and admired, will remain.