How have we all missed this? Just came across this paper, which (at a quick skim) seems to show that people judge an older man to be more likely to be a philosopher than a young woman, and that they are likely to rate the same piece of writing more highly if they think it’s written by an older man than by a younger woman.
(Updated with new link, sadly just to abstract, unless your university subscribes.)
Feminist Philosophers 
I have grown a beard since I began to study philosophy. People now take me more seriously.
Link doesn’t work – gets through to permission required site.
Ok, I am just *fascinated* by the fact that negative mood significantly equalized the halo effect, and that positive mood exacerbated it. Be wary of cheerful philosophers with stereotypic beliefs!
The positive cognitive impact of negative affect reminds me of the evidence (from where I’m afraid I couldn’t say) that scepticism about oneself helps mitigate implicit bias, and the phenomenon known as depressive realism: people who suffer from depression read the prospects of social situations more accurately.
I’m also wondering if the relationship between negative affect and careful thinking helps to explain why grading makes us grumpy? Me, anyway, and as a faculty brat I attest that when my parents were grading we learned to just leave them alone.