I thought I'd make a few quick comments regarding the skin "shader" that hopefully clarify some things.

1) It is absolutely true that the node setup is not ideal. It's something I cobbled together really quickly for personal use and then shared because some people liked it. So please, be very welcome everyone to point out its flaws and make it better.

2) This is probably not ideal as a shader. What it is to me is a collection of nodes that produce small variations in the skin to simulate things like varying pigmentation and small blood vessels. To me, the "shader" here is the PrincipledBSDF node which, fed with the right parameters and texture maps, should be able to produce a pretty good approximation of a basic skin material. In fact, I have a tendency to use too much subsurface scattering as well as specular reflection, i.e. too low a roughness value. So again, if you can improve on that, that's great.

3) The reason I prefer the PrincipledBSDF over the PhysicalSurface node is that it has a builtin Fresnel effect. For my clothing freebies, I have usually included Poser11 versions of the fabric materials that use PhysicalSurface, and if one compares the two versions, one with and one without the Fresnel effect, the difference is quite obvious. So ideally, a Poser11 version of the skin material should use a Fresnel node plugged into the specular channel (I presume) with appropriate settings. I'm not sure what these settings should be, so I never tried, but the experts will probably know.

4) As for the nodes that supposedly do nothing, I can see how that's a bit confusing, but remember that those pattern nodes (Clouds and Spots, respectively) get fed into channels that expect numbers, not colors. Whether those values, seen as colors, are visually indistinguishable from white is irrelevant. For example, the cloud node that pipes into the hue channel of the hsv2 produces values between roughly 0.985 and 1.0. For someone who can distinguish hues well, that produces a subtle but quite visible variation of the skin tone, which is exactly what I was going for. I admit that it would have been better to use maths nodes to modulate the strength of the effect instead of modifying one of the pattern colors, but that's leading right back into comment 1.

Hope that helps.

-- I'm not mad at you, just Westphalian.