[rick404]

I don't like to look at the world in the perspective of moral absolutes. The fruit of the tree of wisdom was knowledge of the consequence of choice.

Now with EC stuff (I like that!) what I tend to see is a deviation from social morals and norms (ie perversions) not so much good going evil...though you really cannot avoid the Good/Evil absolutes in things like sentai series such as Sailor Moon where the characters are so motivated by the fact that they are the righteous defenders of justice. Where would we be without name modifiers like Evil, Dark, or Black (ie Dark Sakura vs Sakura)

As for demons...they tend represent an un-man, something physically and mentally inhuman which is so often successfully represented by a beast of some sort. Humans with the notion that they are so far removed from animals have typically found images of cross between the two disturbing and frightful...which usually suits the purpose of describing what evil must look like.