In the New York Times Andy Martin considers The Phenomenology of Ugly, taking Sartre as his example he seems to think that:
I can’t help wondering if ugliness is not indispensable to philosophy. Sartre seems to be suggesting that thinking — serious, sustained questioning — arises out of, or perhaps with, a consciousness of one’s own ugliness.
Me, I'm (with a lot of people) puzzled why was Jean-Paul Sartre so attractive to women. The immediate answer which comes to my mind is: it's because he was so brilliant and, by the way, women are not always and not only attracted by beauty and the best potentially reproductive males. Then, Mr Martin writes that Sartre "wears it (his ugliness) like a badge of honor". Does it explain why he seduced so many women? I don't think so. I rather suspect some chemical attraction here, like a lot of pheromone emission.