In 1970, an audience of doctors, graduate students, and other professionals listened to a talk by Dr. Myron Fox. They rated the talk and the teacher very highly… but it was in fact complete gibberish.
Dr. Fox was an actor, and the talk was an experiment. The researchers had instructed Fox to give a talk that was full of “double talk, neologisms, non sequiturs, and contradictory statements,” but to deliver it in a very engaging fashion: warm, lively, funny, and personable.
The student evaluations of his teaching were extremely positive. The various professionals had glossed over the nonsensical talk and evaluated the entertainment value rather than the content.
Since then, the “Dr. Fox effect” has been used to explain this triumph of style over substance (or rather, style over sense), and to prove why we should always be sceptical of student evaluations.