I know to watch out for by-products and grains and such. And to Theschmouse: many bad things are allowed under the name "by-products." Meat that's gone bad, including the foam packaging, euthenized dogs and cats, collars included, etc. Not stuff I want my cats eating.
I've tried to convince my dad about wet food but of course, he's looking for convenience and cost, not so much the cat's wellbeing. He loves them and all, but... Fortunately he's agreed to supplement their dry diet with wet food, we just bought some today, actually. I'm lucky he's letting me influence his cat food choices at all. So far, the best food I've found that we can afford is Purina. I know, trash, but it's not as much of trash as, say, Meow Mix. It has less corn and by-products than other options.
Thanks for all the help, guys!
Two cats, a dog, thirteen hermit crabs, seven mice (and babies), four African soft fur rats (and babies), two fiddler crabs, five assorted fishies, a mystery snail, an African clawed frog, a corn snake, a ball python, a California king snake