We use a water squirter -- only water -- to discourage kitties from places they don't belong. They are adjustable from spray to stream. No need to use nasty substances like vinegar. That's cruel and might net you some vet bills. Kitties can be reluctant to share dishes with others, especially if they are not cleaned and well rinsed every day. If adding a little water to kitty's food doesn't work, try offering a little dish of water with a couple drops of canned tuna fish water to entice.