Smiles can be a lot more deceitful than any BRF. And Kristin Stewart's adolescent emo-sulk face expression is kinda hot, hotter than most cheer leader smiles in my book, but it might wear out its welcome after a few decades together.
A lot of people with BRF are just chronic worriers and insecure of how they are perceived/received, but not really bitchy at all.
Back to Kristin: She can smile.
And not just look miserable playing a healthy person (if vampires can be considered "healthy" that is), but also the opposite:
