I've seen this question over and over, and I have to say that when you see it in the toilet, there's just no mistaking. Nothing like that had ever come out of me before. Also, during the cleans I had some movements (not many) that were just the psyllium/bentonite mixture. You can tell.
At the beginning of the cleanse, the MP was very black, rubbery, very formed, and odorless (Now, understand, I have had colonics and been cleansing and changing my diet for awhile, so I don't think mine was that bad compared to many I've seen. Age is a factor too - how long the stuff has been in there.)
Toward the end, the MP was brownish/tan, not as formed, mucousy, and very foul-smelling.
Neither one of these was similar to normal BMs. Trust me when I say, you will know the difference.