Probably (NSFW) What causes the changes in viscosity of poop?

Sometimes it is as dry as a Chilean mummy with Chagas, while other times it slides through like a Telfon coated turd and yet there are other times when it is so tenacious it could be used to hold the tiles in place on the Space Shuttle during re-entry.
What causes these varying degrees of tackiness? Why does it change so frequently? Is it amount or type of food consumed? Does it make a difference if you are a vegetarian instead of omnivorous? Does it have to do with hydration? Is it the amount of liquid drank? Does the type of liquid make a difference? Is it more to do with intestinal flora and fauna and the lack or changes thereof?
Bonus question: Why has the toilet paper industry not made use of the differences to convince us we need several different kinds of paper on hand (so to speak)?