Originally Posted by Happy Jack
Anybody equating themselves with the Joker or referring to him as a hero has a very skewed vision of reality.
Similar to people finding a role model in Tyler Durden. Sure, they have captivating ideas and the world around them is hypocritical and corrupt, but they're still bad people. They should not be looked up to with any seriousness.
Did you read the entire post? He points out that Joker does what Dent and Batman and Gordon set out to do - he got rid of the mob factions. Gambol, the Chechen, and Maroni. All dead because of him. Or in the case of Maroni, indirectly because of him.
I think that's what he means about Joker being "heroic" in the context of the movie.
It all depends on your view of things. Ra's, Bane, and Batman were all doing what they believed was right. If you stretched it, you could also say that Joker was spreading his religion of chaos, and thus also doing what he believed was right, but deep down I don't think he really gives a crap.
Of course, we think that Ra's and Bane and Joker are bad guys because they kill people (as well as sacrifice themselves) for their greater goal. Batman is self-sacrificing but refuses to kill innocents. That's why he's considered the hero out of the lot of them.
And let's face it, Joker does kind of have a point about society requiring laws so the world doesn't go down burning. I think Batman believes that too - that's why he's in the picture in the first place. He doesn't think the laws are doing enough to protect society. But Batman believes that people are, on the whole, innately good. They just need a push toward goodness, which is squashed by fear and corruption. Whereas Joker believes that people are innately selfish, and just need a push to forego law and morality altogether.