Alrighty then, here's a bit about it.
First, your stomach makes everything a liquid to begin with (acid and mechanical grinding). So it doesn't matter what state your food is in when you eat/drink it.
Poo isn't the food that goes in your mouth, it's the dead cells and bacteria that the body doesn't need anymore, along with water and the undigestable fiber. Drinking all liquids wouldn't actually change all that much. Eating foods that can't be digested easily like junk food makes for "shittier" poops, and eating foods high in fiber makes for harder poops. But yeah, you'll always poop if you're cycling cells and bacteria around, even if you're not eating solids. The corn/cheerios that are in poop are made of complex fibers that are hard to mush/digest, so they don't get absorbed.
I'm not an expert either, but I can see where you'd get the idea that the state of the food equals the state of the poo. Anatomy is pretty neat.