Most importantly, however, the halo-effect explanation simply leads to another question:  Where does the teachers' belief that more intelligent students are more attractive come from?  The notion that more intelligent individuals are physically more attractive is a stereotype, and, just like all other stereotypes, it is empirically true, as both the American and British data show.  Teachers (and everyone else in society) believe that more intelligent individuals are physically more attractive because they are.

Basking in unpleasant truth.