I agree with a great deal of what you're saying stretchedoubt. I didn't find the Mayo's comments to be particularly critical...they were more or less saying it wasn't necessary and could be harmful. (I would guess, especially for those who use it to drop 10 lbs regularly...to go to a function and look spiffy in their sexy little black dress)
I also agree with your thoughts on ancient medicine. I personally have little faith in 'western' medicine. I have little knowledge about 'cleansing'...but there has always been a nagging doubt that it is a sensible thing.
The closest I've come to any kind of cleanse, is that gawd awful cabbage, tomato, celery concoction....and frankly I DID feel better in the end (no pun intended)...but in the process, went through waves of shivers and shakes and borderline nausea (similar symptoms described by those who have done a 'real' cleanse). Common sense suggests this can't be good....it's almost like shock.
Anyways, I find it interesting...and have no definite conclusions either way yet.