"Personality" is really just an extension of looks.
Postive feedback loop for good looking men
Good looking males get positive feedback from social interactions, which encourages them to socialize more, and as a result they develop "good personalities". Ugly males will get negative feedback from their social interactions, which makes them introverted and shy. An ugly male will be told "shut up, you're annoying" if he tries to socialize. Everything that comes out of an ugly male's mouth is either ignored or ridiculed. Of course an ugly male is going to develop a bad personality. And even if an ugly male were to magically get a good personality tomorrow, the negative feedback he would get just from being an ugly male who has the audacity to socialize would make his personality shitty again.