I find the violence against outsiders more attractive if it is effective and needed (like post battle sex and the like) than if it is sadistic and they inflict violence on others for the purpose of sex (disturbing serial killer couple voyeurism or Death Eaters torturing muggles during orgies or scenarios like that). I am mostly into hero characters rather than villains, so my mind went to the first place, not the so much the second when I thought of options.