The psychological aspect of Masochistic and sadistic are frightening and I can't judge those who practice such because I am not perfect myself. On the other, when it is the time to say, "that's enough?". How far can somebody go in order to feel and get that satisfaction? There should be a limit, don't you agree?
I don't like it .... Seme is mean. Uke should suprize him when he is asleep and stab a bobby pin through the tip of his dick to see if he likes it as well.