This is something that I've observed both in real life and online on social media (even on this site). As long as a girl's conventionally attractive (tall, skinny, thin nose etc.), she doesn't need to try too hard and can get away with anything, even if she doesn't have an amazing personality and is kinda boring or superficial and/or vapid, other people will not notice these traits and put her in a pedestal (or if they do, they'll cut her slack and excuse her by saying "she's young and immature, so it's ok").
They can even get away with being slightly rude to others or arrogant (in this case rudeness is perceived by other people as honesty and arrogance=confidence), as long as they don't commit any major transgressions.
If you ever dare to argue with them or point out something negative they said, other people will tear you apart and call you a "jealous hater".
Disclaimer: I'm not insinuating that all pretty girls possess these qualities, or that they have a bad personality, (I've actually met lots of pretty girls, who were also kind, funny and had a great personality). But I've also met those with a mediocre or not so amazing
