Regarding the tattoo, I'd need to see what you have on the spec map there.

A tattoo is color inside the skin, not on the surface like makeup. So the specularity of that area should not in any way change just because there is a tattoo there (unless you want it to be a "fresh" new tattoo.)

The faded look of tattoos actually is a result of the thin epidermis that is above it, producing a slight washed-out look as well as the normal skin specular effect. In the comparison you showed above, the tattoo with VSS on it looks normal to me - more realistic than the other one.

However, if you really want it to be more contrasty, then you should make the color map more contrasty. Don't build the faded look into the color map. Let the specularity take care of that.

A color map should have the true diffuse color of the material in it, not including any effect that is produced by the surface specularity or other effects.

In order for the shader to really do its job, you have to design each of the maps to really indicate the truth about that aspect. Color, bump, shine, these all have to be accurate by themselves. Accuracy in this case means they should not look right by themselves. They will look right when all effects are combined. Any attempt to make them look right before the shader does its job will make the shader produce incorrect output.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)