Here's my first try at skin. I took BB's shader model and omitted the Spots function. I then added Miki's specular map node to the Specular_color attribute. As you can see, I'm getting the red shadow artifacts too. It can be better or worse depending on the angle and type of the source lights. Point lights really seem to cause problems. The hair is the default SF black hair shader with the colors tweaked to be more auburn. I'm also getting some persistent artifact on the lower eyelashes. Like a little shiny spot. I have not been able to trace the cause yet. 50 samples per bucket, GPU SF render.