Preferred snack

I would seriously like to know WHY my young son enjoys eating the dog's food. It is probably the most disgusting dog food ever. Sorry Iams, but your food stinks like fish. It's grainy and brown, and though I realize my dog loves it, it turns my stomach. So WHY oh WHY do I constantly have to fish pieces out of Cole's mouth??? He'll stuff some in his mouth and then come over to me, mouth full, knowing well that he's not allowed to eat it. Then he smiles mischeviously, which causes nasty brown fish drool to travel down his chin and land on his shirt. Gross.