If you believe in it or not I am sure a Colon Cleanse might be good for everybody.
I would guess that most people with regular BM's are pretty clean.
This whole discussion was started, if I remember right, after Elvis and John Wayne died.
Here is a link from the debate forum, with reactions from colonix and Oxypowder and some pictures from a poster.
After more than 4 years on CZ I know some people indeed have reported the MP. So at least do any cleanse at least once and if you see anything or not you are off to a good start.