Our first two greyhounds, Paula and Buddy, have never shown any interest in the kong. When we first got Paula, I tried stuffing it with peanut butter, but soon found out that she really doesn't like peanut butter. I even tried yogurt, which she loves and will eat from a spoon. Buddy just doesn't like to lick things, or chew very much.
A friend who has a beagle gives it a stuffed kong each morning when she leaves for work. She has mentioned peanut butter, fat free cream cheese, and liverwurst as being the dog's favorite kong stuffers.