The reason pineapple works (for some dogs) is that it has bromelain, an enzyme in pineapple that digests protein....a good digestive enzyme & probiotic might help if your dog(s) doesn't like pineapple.
https://pet-health.knoji.com/benefit...ine-illnesses/
Ann is right, there's something in the food that's not digesting thoroughly & it still smells like food to them.