And for this talk about Joker remaking his personality all the time, we never see, he is almost always same nihilistic monster he always is, he might just might have different theme on that this week. Superficial things change, the core personality stays the same, when he is last time we say a harmless Joker or even helpful Joker? The personality doesn't really change. He is not "super sane" that just seems like a con on his part.
There are lots of psychopathic aspects to Joker's personality, look at these aspects and tell me Joker doesn't fit into a lot of them: