I make evil sims regularly they do more on their own if it's paired with other bad traits. Mean and hotheaded ... if hotheaded they get angry more often and act on their own. Other negative traits can bring out more action because of being uncomfortable or tense and also and of course skilling up the mischief skill can help.
Personally though I make a more evil sims with that I like to see as a sociopath if not a down right psychopath so I don't want them to be outwardly mean to other sims.. or get caught at doing bad things. I like them to be charming and nice but still enjoy the suffering around them. So often the trait is pretty spot on for the character I'm making.