Roger Scruton has an interesting article in City Journal about modern aesthetics. He argues that since 1930 or so, one of the major themes of the arts -- and a new one in the Western tradition -- has been to intentionally depict ugliness:
I used the word “desecration” to describe the attitude conveyed by Bieito’s production of Die Entführung and by Serrano’s lame efforts at meaning something. What exactly does this word imply? It is connected, etymologically and semantically, with sacrilege, and therefore with the ideas of sanctity and the sacred. To desecrate is to spoil what might otherwise be set apart in the sphere of sacred things. We can desecrate a church, a graveyard, a tomb; and also a holy image, a holy book, or a holy ceremony. We can desecrate a corpse, a cherished image, even a living human being—insofar as these things contain (as they do) a portent of some original sanctity. The fear of desecration is a vital element in all religions. Indeed, that is what the word religio originally meant: a cult or ceremony designed to protect some sacred place from sacrilege.
Scruton provides several examples of the glorification of evil, not in the sense that evil is represented as good (e.g. Nazi propaganda films), but that evil is praised for being evil. It is a rejection of the hero/journey motif for a villain/destruction one and a nihilism that is all too present in postmodern life, from Robert Fisk's praise for his attackers to the movie Natural Born Killers. It is an urge to simultaneously destroy and be destroyed.