The garish corpsepaint, the screams of the guitars and the caveman grunting lyrics about vomiting baby parts doesn't frighten me or cause me any sense of unease. If anything it makes me laugh, black comedy intended to offset the terror. It might work for a splatterpunk movie or something Eli Roth would produce, but not if you really want to unsettle people.
I know peoples tastes are subjective, but in my case this is so much more immersive and when people hear it they react to it. I like to play this kind of stuff at work so I can judge the reactions of my customers. When I play metal they ignore it completely.
I saved the best for last, but then, I am biased.