I played with a sim once who was evil and romantic (I forgot his what his third trait was) and had a lot of fun. He was in the criminal career which I had never played, and I switched him back and forth between the Public Enemy and Serial Romantic aspirations. It was fun causing a bunch of chaos, starting fights, and having him cheat on his wife with several different women, because I usually just play happy families.
I use other negative traits sometimes, like unflirty (although I don't really see that to be negative), squeamish, and hot-headed. The only ones I avoid are jealous, hates children, and kleptomaniac. Jealous and klepto are just annoying because of how often they get tense, and I avoid hates children because I'm a family player.