The temperature of the food . Most cats don't like food which is too cold. Serve food at room temperature or warm it slightly to mimic the temperature of fresh caught prey. The food bowls. Cats dislike deep or narrow food bowls which constrict their sensitive whiskers.
Some types of plastic give off smells which, to the cat, smells as though the food is contaminated.
Some are allergic to plastic and develop a skin rash from plastic food bowls. Switch to a shallow china or metal dish. Cats may be willing to use narrow bowls to get to a treat food or forbidden food, but not for everyday eating. Cats don't like the smell of stale food so use a clean bowl for each meal and keep the eating area clean. Stale food could harbour multiplying bacteria which can cause food poisoning.