Spanking's pretty vanilla — mainstream — and it's not something that can really cause serious damage. It's also a good way to explore your reaction to pain in a controlled environment with sexual overtones.

（ aka: yes, it's a good beginner activity. ）

But it's not for everybody. I think because a lot of cultures treat it either as a corporal punishment for kids and adults, or one that's intended to humiliate it can carry some heavy connotations for some people, so it's okay if it's not your thing. For some people that's the allure. For others it's just the pain. The glutes are the biggest muscle group in the body, and in most cases the strongest — and there's no vital organs at risk of being immediately affected by a spanking, so people can take a lot of damage there before it starts to become a problem. Doesn't mean you can't cause permanent damage, but the risk is probably the lowest of anywhere else on the body.