The first thing I look for is the first ingredient on the ingredient list, and I avoid ground corn as much as possible. If you want less waste, you want to do the same. Pets don't digest food mostly consisting of corn that well. That is why you want to look for food that has mostly meats and vitamins that can be easily digested, creates less waste and is the best for your pet's health in general.
Many of us who are parents to cats notice that when we pet them, they sometimes turn around a bite our hands. Why do cats do that? Dog parents smugly state that their dogs wag their tails, pant and lick their hand. They claim that dogs don't bite the hand that pets them. While this is not a competition between cats and dogs, I'll give the dogs this one. I had a beautiful dog for many years (she passed away at 12) and she never bit me when I petted her. However, each and every cat (except one) has nipped at my hand.