It's at this point you'd probably want to go read David Foster Wallace's essay "Consider The Lobster", an assignment he took from (I shit you not) Gourmet Magazine, which begins with a sort of Illinois Country Fair style travelogue from the Maine Lobster Festival and "ends", if you can call the back 2/3rds of an essay "ending", in a discussion of the meaning of pain and its applicability to the specific nervous syste…
If we consider an extreme case of someone going through a horrible torture, but the next day waking up as healthy as before, and without some kind of mental illness, and without losing significant amount of his time, or opportunity, would it be any different than a game? Would most people try such a game, where they play for someone getting executed in middle ages?
My guess is they would, so fear of the pain is misplaced, and death is the horrible part. And therefore killing painlessly doesn't let one off the hook, since it is still killing. (And if one thinks killing is ok, then some amount of pain should be ok too.)