So sure, start with a slogan. But don't bother wasting any time on it if you're merely going for catchy. Aim for true instead.
Since I hold no judgments against my characters, no matter how heinous they might seem, I present them as real people with their own moral centers. We might feel those moral centers are mis-calibrated, but they are there and are the rudders that propel them. This makes reading my work a visceral roller coaster, 'cause the reader must embark on the journey of the protagonist equipped only with his or her own moral center.