Many people love to prepare foods in a cast iron skillet, but as much as folks love it should be known that you can't cook everything in cast iron. There are some foods that just aren't meant for cast iron. Smelly foods like garlic, peppers, and some fish can leave a lasting odor in your skillet. If your cast iron pan is new you also want to avoid sticky things like eggs. You also don't want to cook delicate fish like trout and tilapia in cast iron and watch out for acidic things in your cast iron pan as well because they can react with the metal of your pan and change the color.