“In fifty to one hundred years,” Brian Droitcour said during his lecture on “Vernacular Criticism” at the New Museum of Contemporary Art, “the exhibition review might become a sonnet.” The arts of literature and theater were certainly on his mind, as he began his talk by reciting two of his cheeky Yelp reviews on venerated New York art institutions—the Frick Collection and the Solomon R. Guggenheim Museum—from memory for a full auditorium.