From what's already been teased in the trailers, it's pretty clear that they took a lot from the comics and from other media treatments of the Joker--no matter what the spin doctors tell you. It just might not be in line with whatever the current version of Joker is supposed to be in the comics. But you can see a lot that's been taken from THE KILLING JOKE and THE DARK KNIGHT RETURNS. I don't see this being so much different from Marvel movies where they take the essence of a few Marvel comic book plots, jam them all together and create a movie that is an adaptation, but a very loose adaptation of the source material.

I think the promotional machine is worried about trying to sell the movie to people that usually reject comic book movies and also trying to sell it to people that expect a panel for panel adaptation. They're trying to get the non-comic book critics to give the movie a chance and they're trying to prepare the hardline comic book fans so they don't lose their nut when they see that the Joker has a red nose. I'm not sure if they can really innoculate themselves against either faction. There will probably be a lot of angry vloggers declaring that JOKER destroyed their childhood.