My feline testing supports this theory. Bar of chocolate sits undisturbed on countertop, while entire stick of butter gets eaten in seconds.
My cat won't eat anything but her canned cat food, she won't eat that if it has any sort of fish in it. But she will definitely let you know when her bowl is empty!
My cat goes nuts over my homemade chocolate milk - just sugar and some unsweetened cocoa, sometimes a drop of vanilla. She reacts about the same to store-bought chocolate milk as she does regular milk.
I guess I'm just a good cook. :)
My cats love oleo, icecream and icing on cake. Whoops!
Or a greasy frying pan left on the stove overnight gets licked clean.
My kitty comes running whenever a can is opened... but declines when the stuff inside is only diced pineapple.