Does this still qualify as a sexual fetish? It seems more like a fetishization of the violence itself. This raises interesting questions. We tend to view violence as always negative, even if it is a necessary evil, but can it still be a negative thing when the effect is positive and desired by both parties? Certainly in these select circles, the violence is considered a very positive thing. Why do these people find that their bodies crave pain and violence? Is it the violence itself they enjoy, or only the specific act of spanking? Evidence would suggest the latter, but how does this enjoyment relate to masochism in general?
The article is here: http://www.salon.com/life/feature/2011/02/10/inside_world_of_spanking