This one for proffies argues that students evaluate female professors lower in a way that is impossible to adjust for. This one for students argues that prettier students get higher grades.
And I will admit that this past fall semester, on the day I was going to give course evaluations I stood in the bathroom thinking if I should take time to curl my eyelashes so that some recency effect of appearing, I don't know, more awake, might tick those boxes up a notch. And then I thought, "You know, [male colleague in the office next to me] doesn't think about this kind of stuff at all." And then I curled my eyelashes.
A friend posted the first article on Facebook and one comment was, "With the exception of a modest number of students, these are popularity contests, based on two things: how cool do you think the teacher is and were you given too much work by your standards?"
I think that is right on the money, but I do think I will stilll be having mirror debates.
I am inspired to use the blinded grading mode on the LMS for the students, but there's not such a thing for course evals, unfortunately.