The type of pain being relevant makes a lot of sense. I guess that goes for all stimuli - just because I like fairly noisy and repetitive music doesn't mean I enjoy listening to construction noise.

Does it have to be events of pain or can it be continuous? Is predicament pain like in the picture enough to make you cum?

I find the thought of you hitting your shin or something and having to suppress a moan very charming, by the way. :)