It's easy to confuse erotic humiliation with BDSM; however, according to my very unscientific research, the two are not the same. The emphasis in erotic humiliation is just that--humiliation. The humiliation can take many forms; verbal, such as scolding or name calling; animal play, making the submission eat or drink from pet bowls; erotic objectification, requiring the submissive is used as furniture, or any form of sexual embarrassment. Obviously the spectrum is vast but the basics are pretty simple: its any time a consensual person is turned on by being demeaned or demeaning others.
The theories that seek to explain why this works focus on the emotional and physiological responses to humiliation and state that the high level of trust and communication that make this work enhance the overall experience. Also, that the area of the brain that responds to emotional pain, including humiliation, is the same as the one that responds to physical pain. Thus, the humiliation is a very strong emotional trigger.
Belle de Jour is an erotic humiliation classic, different from O and 50 in that the heroine, who feels disconnected from her husband, seeks out the humiliation. She begins a double life: call girl by day, proper Parisian housewife by night.
The film, starring Catherine Deneuve is a visual feast. The trailer above only gives you a taste. The whole thing is worth hunting down. I suggest watching it twice. The first time for the story, the second to catch the subtle things you missed the first time.
Curious for more? Try this article from The Village Voice by Tristan Taormino. It recounts the author's experience with a BSDM class on erotic humiliation.