Why do some models have no face?

[humbawe1]

I stumbled across this amazing Chinese/Japanese soft erotic site called Premium Link Upgrade and has another site called 'beautyleg'. All the models are gorgeously stunning. They seem to make everything around me freeze in time they're so beautiful. But there are a couple of models (the ones I'm talking about here are named Emmie and Minna) that never show their face in any pictures. They have great bodies and are wearing just perfect lingerie and pretty clothes. In every picture, they have their head turned or obstructed by their hair or shot in a way so that you don't see them. I don't understand why though? Is it because they're ugly or something? Do they not want to be identified? I still want to see their face. It would suck for it to be that they made to hide their face because it's not pretty enough or something stupid like that....