gail:
For me, that needs to be between consenting adults.
I guess this wasn't made clear in anyone's posts so far, so I'm glad you brought it up. I had been assuming we're obviously talking about consenting adults, but of course 'assume' makes an ass out of you and me - just me in this case...

So, since I'm explicitly and very clearly on record here with my declarations that I looooove cruelty and humiliation - I'm, like, totally into it - let me also go on record to explicitly confirm that I obviously meant between consenting adults.

As to your other point:
gail:
I don't think embarrassment and humiliation are necessary part of the same continuum
You're right, and it becomes easier to see (for me at least) if I'm applying it to something besides spanking. Sometimes embarrassment is necessary and in fact totally called for, in the process of making someone account for what they've done. Humiliation on the other hand is never necessary and is pretty much always uncalled for.