You are more generous than I. How can anyone be a pet owner and not notice the extraordinary talents of their animal? If the animal doesn't eat-- its because there is a very good reason. Bad food is one of them.
I am a new first-time dog owner (April 05), and I have been humbled at how much I didn't know. Even though I read all of the SPCA literature* and bought and read a dog health-reference book and a dog psychology book, I have learned so much from this dog (a fun, smart, gentle yet protective of her domain 9-year old female Queensland Heeler). When I first saw this article I almost cried, and raced to read what brand (I buy Science Diet Senior). My dog only eats if I'm in the room with her, but it took me a while to figure that out and before I did, I discovered she likes peanut butter or the broth from a baked chicken mixed in with her dry food. I may be too stupid to live but I can easily see how easy it would have been for me, prior to reading this article, to attempt to tempt my dog with a little spoonful of peanutbutter mixed in if she hadn't eaten anything but her treats (100% chicken-jerkey for dogs; forget the brand but it's a killer deal @ Costco) in two days. On the other hand, I would be immediately concerned if she didn't want to eat her canned food, which she almost inhales.
None of the dog literature I've read so far has mentioned this behavior would be a major alarm, and I am so grateful I don't buy that brand. I love my dog and I hope she stays healthy for a long old time.
*SPCA literature on how to introduce cats to a new dog = AWESOME!