On the practice of judging politicians based on their knowledge of the prices of common goods, as occasioned by a recent such episode in France:
Perhaps it would be possible to rank politicians (or people in general) by the prices of which they are aware. Those who know the price of an Aubusson tapestry, for example, but not that of a pain au chocolat would be of aristocratic or industrialist conservative type; those who know the price of a pain au chocolat but not of a McDonald’s hamburger would be of good cultivated social democratic type; while those who know the price of Coca-Cola but not of fennel would be of the proletarian populist type. Political debates should be replaced by lists of goods of which the candidates estimate the current price.
Or in shorter form: “By their knowledge of prices shall ye know them.”