From an interesting Edge talk by Jonathan Haidt on The New Science of Morality:
I think taste offers the closest, the richest, source domain for understanding morality. First, the links between taste, affect, and behavior are as clear as could be. Tastes are either good or bad. The good tastes, sweet and savory, and salt to some extent, these make us feel "I want more." They make us want to approach. They say, "this is good." Whereas, sour and bitter tell us, "whoa, pull back, stop."
Second, the taste metaphor fits with our intuitive morality so well that we often use it in our everyday moral language. We refer to acts as "tasteless," as "leaving a bad taste" in our mouths. We make disgust faces in response to certain violations.
Third, every culture constructs its own particular cuisine, its own way of pleasing those taste receptors. The taste analogy gets at what's universal—that is, the taste receptors of the moral mind—while it leaves plenty of room for cultural variation. Each culture comes up with its own particular way of pleasing these receptors, using local ingredients, drawing on historical traditions.
And fourth, the metaphor has an excellent pedigree. It was used 2,300 years ago in China by Mencius, who wrote, "Moral principles please our minds as beef and mutton and pork please our mouths." It was also a favorite of David Hume [...]