Not maybe, that's exactly it. There is something very erotic to see a strong man's body, the shirt off, hands tied loosely behind the back. A whip is playing over his back, lightly in the beginning, then more and more strongly. Stop for a pull of his hair and massage of his crotch, then some more whips and watch his muscles strain and move. Then the sarcastic look thrown over his shoulder , as if saying "This is all you can?", then his words "NOW, untie me" ....Maybe just the thought of transgressing by topping you is erotic for her.
Something like this. Nothing humiliating at all, just erotic and sensuous.