Sometimes it's just a fashion affectation. One of my good friends from college has been "Goth style" on and off ... but she had a good childhood with loving parents, has a college degree, a husband and a sweet little toddler, and survived breast cancer treatment like a champ.
I agree that lots of them its just "I like black and look good in red lipstick".
Granted, the only ones I've known were this one particular woman and her circle of friends, who were all just as damaged as her. Interestingly enough, her husband was a real fundementalist Christian (how the two of them got together I'll never know). :)
Okay, somebody needs "What not to Wear".