For some people, certain types and amounts of pain is actually processed as a basically enjoyable thing. Other types of pain are still processed as pain, but is still something they want to happen and enjoy on a different level.

The distinction that I make is physically damaging versus not. So good pain that I like is pretty simple (hair-pulling, spicy food, moderate heat, etc.); good pain that I don't like would include a lot of the pain caused by exercise; bad pain that I like would include excessive heat (for some reason damaging levels of heat are easier for me to enjoy than other sorts of injury; I've burned myself before by walking on hot pavement that wasn't quite too hot to enjoy), and bad pain that I don't like would include stubbed toes, sprained ankles, and the like.