The trailer really embraces that tag line "Justice has a dark side." And it seems to be hammering home the argument that when this thing hits next year, DC will again prove that they can do super villains on an entirely separate level from Marvel (what do you expect when the Squad is loaded with Batmna villains?)
Though for the insanity thing....
I'm feeling certain that mental issues are going to be a major theme of the movie. Belle Reve looks like the type of dank, spartan, and deprived holding facility that would aggravate any mental health issues you might have before being incarcerated there.
Harley's dissonant serenity to her surroundings and almost innocent tone implies we're going to see just how disconnected from reality she really is. This is someone who's hopelessly lost in a horrible relationship and has kind of regressed a bit. Meanwhile, Joker is full on sadism and psychotic glee. Whereas she seems ignorant of her insanity and evil ("Huh?"), he revels in it.
Diablo and Croc both seem to be a different sort of monster from the clowns, what with the way they look a bit more blatantly monstrous. But we see Diablo toying with his powers and looking at himself in the mirror in a kind of evaluative way, and Croc seems to be glowering and trying to conceal himself a bit behind his hood. These guys may be the tragic monsters who've had to embrace their dark side to survive, Croc from his physical transformation and Diablo from his infernal powers.
Smith seems to be putting a bit of depression or apathy and weariness into the little bit of Deadshot we see here, which would fit Deadshot's traditional death wish. I'm thinking he'll be the film's protagonist, with his journey being the discovery that he actually enjoys life on the Squad, as horrifying as that concept may be.
Enchantress looks to me to be the most blatant exploration of the theme. When we see Moon under the Pentragram, she looks vulnerable and scared. She looks like a kid. When we see the Enchnatress later, and in the Poster, she looks much more malevolent, with a kind of vacant look in her eyes. I think the shots in the trailer are supposed to signify how she has to fight her dark side, and seems to be losing.
. David Ayers is a fukking bad ass and a beast. This is gonna be a comic book version of training day if that makes sense 
. I interviewed David and Michael Pena for the movie "Fury" and Michael was saying how they were learning to box and David would beat everyone up, even his leading actors.
