There are so many hacks for rendering skin. Truly modelling the microfacets for specular reflection is not possible in realtime, and it's not worth it for most animation. The most common simple method for CG skin in games is to render it first with high sharp details, write out every pixel that is skin to the stencil buffer, then do basically a blur + reddening pass if you have thickness information. Hair can be done similarly, but really requires a sharp anisotropic pass instead of blur to be done right
There are so many hacks for rendering skin. Truly modelling the microfacets for specular reflection is not possible in realtime, and it's not worth it for most animation. The most common simple method for CG skin in games is to render it first with high sharp details, write out every pixel that is skin to the stencil buffer, then do basically a blur + reddening pass if you have thickness information. Hair can be done similarly, but really requires a sharp anisotropic pass instead of blur to be done right
The skin had the odd smoothness that is an artifact of CGI.
An interesting thing about human skin is that it is covered in countless tiny, nearly invisible hairs. This is one of the reasons it is difficult to get fingerprints off of human skin. Most CGI skin just isn't fuzzy enough for someone with sharp eyes.