I have no idea what the humiliator feels, but I know as the humiliatee it's quite hard to explain what you feel.
It's a little like...having doubt removed, which puts you at ease, at least in the situation my girlfriend and I are in.
Instead of wondering 'Is it big enough? Is it really that small?", it makes everything simple. Yes, it's small, and she now doesn't have any trouble telling me so, and for some reason I am still to understand, I enjoy that.
She isn't nasty in doing it, she just makes it fact that I have a small cock, she says that it does everything she wants it to when we have sex, and that's good enough for me.
In a way, knowing that she thinks it's small removes some inhibitions, and just lets me enjoy our sexual relationship more. It's small, she likes telling me, I like being told, pretty much that simple.
I don't feel like she respects me any less, in normal day to day couple relations, everything is still the same, she doesn't use my size as an insult, just a fun thing to do in the bedroom.
Demonitron