Odysseus killed with wild abandon, shagged a lot of people who weren't his loving + faithful wife, and sacrificed his men like chess pieces in favour of his own survival.

By modern standards he'd probably be a bit of a shady hero, but because his actions aren't analysed at all in the Odyssey, the reality of that is very glossed over.

What *has* changed, at least in relation to Odysseus, is our perception of ethics and equality. It was quite alright for other people to die while Odysseus lived, because men weren't equal and he was obviously more important than the other dudes. It was okay for Odysseus to not be faithful to his wife because he was operating on a different set of moral and social expectations from his wife.

And it was okay for Odysseus to be bloodthirsty, because our definition of "justice" has changed. The ancient Greeks understood justice as a concept which meant (in effect) someone who follows their pre-ordained fate. A just life is one which adheres to the plan of the gods.

I am not sure that the actions of "heroic" characters has changed that much, in a strictly objective sense, but I do think the context surrounding those actions is more closely examined these days. Maybe I'm wrong; just my take.