[i_dont_know_]

I think what I'm getting at is that there are different types of 'pain', some that we'd consider ethical and some that we wouldn't.

Constantly subjecting a person (or some abstract simulation that responds like a person) to the equivalent of continuous bodily pain would be deeply unethical, but, say, giving a person clues towards solving a puzzle would be considered less so.

Overall, I think you're right though, if we somehow discovered we've created simulated people (or sentient beings) then we probably shouldn't use them to solve arbitrary problems.