I have cleansed with Dr. Natura's Colonix product several times over the past few years and I've personally never had a bad experience with the product. I've always expelled some rather horrific looking matter and felt better after the cleansing treatment was over.

Having said that, I think people that say "Colonix doesn't work!" may not be following the recommended guidelines. The instructions are included for a reason, and you can't expect to see the best possible results if you're unwilling to make a few changes during the cleanse such as cutting out alcohol, caffeine, and drinking more water.