Corn, soy, and wheat are three of the biggest culprits as far as food allergies in dogs go, and finding a brand of dry dog food that is free of these ingredients can be tricky. Itchy, red, flakey skin, and a dull coat are common symptoms of food allergies. Always check the ingredients on your dog's food, and always check with your veterinarian to eliminate other health problems that may be causing dermatitis.
Link here:
About Dogs - Corn and Soy Free Dog Foods
Hope that helped! There's TONS of information on reading labels and such online! I've read tons and tons of stuff in order to make some sort of informed decision!
Wow.. you people are fast! LOLOL