Apparently for skin, what we see is due to mainly subsurface scattering. Only 5-7% of the incident light is directly reflected back to the environment with the rest being scattered inside the layers of the skin. (A Biophysically-Based Spectral Model of Light Interaction with Human Skin by Aravind Krishnaswamy and Gladimir V.G. Baranoski)
Wondering if this is how beauty camera works? Applying some fake light to the original photo?