I think it's okay, so long as it doesn't...mess with your life, I guess. T: Like change your outlook on things and/or the way you think. It's a good way of venting, and I've done it plenty of times.
Morbid/gorey/disturbing art isn't necessarily bad on its own, especially if done tastefully. I met a member of another forum who posted drawings of rotting corpses and the like; it was gorey, yes, but the quality of the art itself remained.