It needs to be what the herd needs it to be. When you upset the herd there are bad respones because the hernd needs to function as a group. Thats it.

We look back at Hilter and say hes evil. The people in Germany did not see it that way at the time. He was a hero. He brought together his herd.

So it depends on a society's perceotion of the events and what it does to that society at the time.