Alyssa does pet sitting and we always notice when the doggies are fed "doggie fruit loops". My hubby coined the phrase when he opened a particular bag of puppy food from one of those neurotic dogs who had accidents all over the house.
This is a far call from a scientific study but when we have dogs with uncolored dog food we seem to not have the same aggression or potty problems as dogs with obviously colored food. The best food that we've found to not contain any color, flavoring, or obvious preservatives is Kirkland brand from costco. It also doesn't list animal biproducts. We've never had a neurotic dog or an accident dog who was fed Kirkland.
So, if you're going crazy over your dog, just try a little experiment. Let me know what you find.