I noticed that one of my cats has VERY stinky poo when I give her any moist food. This is a major problem in the litter box area, which is also the human's litter box (bathroom). Based on what I know of human digestion, extra smells in the bathroom means something is not being digested quite right.

Since both cats seem to eat and live healthy with the premium dry food (Iams) I have given up on adding any moist food. A lick or two once in a while of some tasty human food is all they get extra.

Just so you know, I've been using the same dry cat food for 7 years, and none of my cats has turned me in to the food police!