ANOTHER THEORY—PEOPLE WHO SMILE CAN’T BE TRUSTED. Meyer and Jeeves give a different answer to the question. Meyer quotes Jeeves: “By the 17th century in Europe,…it was a well-established fact that the only people who smiled broadly, in life and in art, were the poor, the lewd, the drunk, the innocent, and the entertainment.” Meyer quotes a French writer in 1703 who criticized “people who raise their upper lip so high… that their teeth are almost entirely visible.” Jeeves includes paintings by Jan Steen, Judith Leyster, Franz Hals, and Caravaggio which show that smiles were associated with a lack of dignity.
I read an article years ago in the New York Times Magazine which said that even today Greeks tend not to trust people who smile too much.