I'm intrigued by humiliation, having never really experienced it in a BDSM context before. In many ways the physical signs of embarrassment is very close to plain old sexual arousal: flushes of heat as blood drives towards the skins surface, heightened awareness of place, increased heart rate. All very powerful. I am particularly interested in the psychological elements ever since The Photographer commented on how there was an element of embarrassment when we play and he serves me. Certainly, this feeling seems to increase his arousal and general sensitivity: when we were fucking and I reminded him of his position in servitude by idly musing over getting him to introduce himself as my slave in a club or offering him out to people, he bucked, twisted and got generally hotter under the collar. Which is always nice.
Humiliation is very different from objectification or pet-play. Only a human can be humiliated: animals and tables can't, so within a scene the position of the submissive is very much that of a person, suffering from the conflicting desires of their situation. Context is clearly very important, as is an audience, to a certain extent. I imagine that having others watch one's submission or to be publicly humiliated would be very intense. There is also a fine line between sexual humiliation and just downright embarrassing and silly. Apart from causing an attack of the giggles I think there are probably situations that could devolve into farce and end any serious quality to play. Humiliation is a tool of oppression - to push down by dint of superiority, to force someone through something they find uncomfortable because you are more powerful than they are, because they give you that power.
For me, I would not feel humiliated by acts such as crawling on hands and knees, eating from a dish on the floor or introducing myself as someones slave. The latter is something of a badge of pride, I guess, and I do relish the idea of being owned: it makes me feel special, wanted. The former are things I find arousing because they are acts of submission, not because they make me hot with shame. In as much as I am able to reason whilst in a submissive headspace (although I often pick apart my motivations afterwards, to share with you all) anything I am asked to do whilst submitting is something I do for my Dom, and so is perfectly normal, therefore not at all humiliating. Of course, it could just be that I haven't done anything yet that I personally find humiliating and the feeling is yet to come. Never say never and all that.