Some dogs are what trainers call "food-motivated."
They'll do almost anything to get a snack. This can be totally useful for training purposes, but not so useful when you're trying to get them to calm down at dinner time. While I've been able to train my dog to wait before gobbling down his food, it was difficult and took a lot of practice.
At the Beloka Kelpie Stud Farm in Australia, the handler of 11 dogs has a ton of practice teaching them to behave when it comes time to eat. What he manages to pull off is so impressive.