I learned the hard way where my preferences lay. I love gentle and 'teasing' type humiliation. Things like pet names and embarrassing instructions like going without undies or the like. However, I found I have a very strong and nearly violent reaction to outright degradation and anything meant to make me feel worthless.
The problem is, it's often hard to explain just where that line lays to people. A lot seem to think there's no difference between humiliation and degradation. I've had enough people trying to hurt and degrade me in my everyday life to last several lifetimes, I really don't want that with someone I care about.
I think it's one of those things that really shows how important communication is in any relationship, but especially a BDSM one.