Those of us old enough to be getting colonoscopies will have experience with true purges (4 litres of Klean Prep!), since the doc needs you to be completely empty in order to see any small polyps (or worse). I've had the (very) occasional enema and yes, there is a "stimulating" element to them. I suppose colonics are like that, maybe more so. But, I think the putative health benefits of enemas, colonics and dietary "purges" are nonsense. You want to purge? Exercise and drink lots of water. You want regular bowel movements? Eat more fibre. Your bowel is self-cleaning if you treat it right.
The pre-colonoscopy purge is definitely not fun. You drink 4 litres of unpleasant-tasting fluid, then spend two or three hours shitting. But the health benefit, in that it's prep for a scope bowel exam, is proven. You really don't want bowel cancer in your life and the best prevention is a regular colonoscopy to find and remove any pre-cancerous polyps. I say that since my father is stage 4 bowel cancer. He was one of those who kept saying "something's not right down there" and left it years too late. If you're 50 or over, every 5 years, get your doctor to set it up for you. I go to the Rudd clinic in downtown Toronto and would recommend it.