A key source of variation in academic salaries is the ability to obtain an outside offer. Hiring a senior academic, however, is a bit like buying a used car - one that is on the market is much more likely to be a lemon. Someone who is charismatic, likeable and well-organized - the traits that our hot professors seem to possess - may be more likely to convince a hiring committee that he's not a lemon. An outside offers story would be an alternative explanation of why we do not see a hotness premium for women - women are more likely to be in situations where they are unable to move because of family or other commitments.If the study had shown that female salaries were increasing in hotness, I'd expect complaints about how econ departments, typically heavily male, pay extra for eye candy.
When we estimated the returns to hotness, we controlled for research productivity - number of publications, citations, and holding a Social Sciences and Humanities Council research grant. Yet there might be further indirect effects of hotness if, for example, people who are fit and healthy are more likely to be hot and also are more productive researchers. We explored this possibility, but didn't find much - the relationships between hotness and research productivity were generally positive, but almost always statistically insignificant.
Where there is a stong relationship is (not surprisingly) between students' evaluations of a professor's hotness and their evaluations of his or her teaching. Hot male professors received significantly higher scores for clarity (0.76 on a 1 to 5 scale) and helpfulness (0.68 on a 1 to 5 scale) than their not-hot counterparts. There was very little difference, however, between the hot and the not in terms of students' ratings of the professor's 'easiness'.
But the pattern for women was quite different. Hot female professors had somewhat higher clarity scores, but the difference wasn't statistically significant. Where hot female professors received significantly higher evaluations was in terms of helpfulness (1.0 higher on a 1 to 5 scale) and "easiness" (0.43 on the same 1 to 5 scale - how I have struggled and failed to avoid the inevitable innuendos).
As a feminist, I find the results in one sense profoundly depressing. Men can have it all - be attractive and also well-paid. Women have a choice - you can go for it, be tough, negotiate a high salary, have high expectations of your students. But don't expect to see a chili pepper beside your name any time soon.
Now let's suppose, for sake of argument, that there's no correlation in New Zealand: salaries are invariant to hotness.
As an exercise for the reader, work out the equilibrium where labour is mobile.