I've talked a bit in the past about sissies and fetishes for humiliation.
One of the things in public humiliation that tends to get to them in fantasy or reality is the reaction of women (or men). While many may fantasize about playful interaction, in most cases a reaction from afar is the most they can hope for. These might range from a double take to some playful whispers to a friend to outright disgust. Overall I think that most of these reactions can't be faked... or at least not well.
Having been humiliated in public before, I've found that things like a natural surprise, shock, smirk, or giggle just don't seem to represent well in a staged setting. With this in mind, I can imagine it would be hard for someone who really enjoys public humiliation to be able to get off to humiliation porn. Most pictures attempting to display shock or surprise end up coming off completely fake and unnatural.
I'm not a huge fan of being humiliated publicly but I have stumbled upon one picture that did seem to get my blood pumping. It's not perfect, but better than most attempts at looking shocked.