It is yet another sub-genre for rock music, and as suggested, it infers music which appeals to hormone-ridden teenagers of a sensitive persyasion.
The Daily Mail - never a paper to let a scare story get in the way of the truth - did a major feature last week inferring that such music inspires suicidal thoughts, but then again, they think women voting frightens the horses, so don't take it to heart.
There is a loose dress clode applied, but like all things tribal, some fans will adhere, some will ignore, and the whole thing will move onto something else shortly.