Why Are University Professors Such Schlubs?

For no reason whatsoever, I am reproducing below the results of a decade-old bit of research that uses student scores from RateMyProfessor.com to construct average hotness scores for different academic disciplines. The authors used a scale from -1 to 1, which is entirely nonstandard in the field, so I've renormed the scores to the more generally accepted scale of 1 to 10. I assume professorial hotness is, in fact, average, which means the various disciplines should probably range from about 3 to 7. But not a single one even breaks 5.

What does this mean? University professors are slobs? 18-year-old students have really high standards? Movies and television have conditioned us to think of really hot actors as average, thus making us all disappointed with real life? I dunno. What's your guess?