I like to poke darker subjects, like experiments on humans, but I find that 99% of the time it's not done for roleplay value but just because these people get off on it. When I think of this, I think of it being death-camp nazi experiment style - it's definitely bad, it's definitely not ethical, and you're probably not using willing subjects. But it's for the sake of science. 

What I'm not really interested in, and what it seems to be portraying 99% of the time, is sexual fantasies. :lol