"You Can't Judge a Book by the Cover" is based on a sixteen-bar blues structure that "boasts a beat that's utterly compulsive and primordial, but closer to a way-speeded up walking rhythm than to the standard Diddley pattern", according to
Richie Unterberger in a song review. Percussionist
Jerome Green added
maracas to the recording, which Unterberger calls "an utterly entrancing rhythm that does much to add to the power of the song". Dixon's lyrics describe a variety of situations to illustrate that one should not judge them by their appearance, before repeating the title phrase: Diddley's original recording breaks the
fourth wall by encouraging the listener to turn his or her radio up after the first verse. ==Releases and charts==