Why does the satin fabric appear so metallic to me while it is a dielectric material It started with making a skin shader. I am still convinced that we see a rough colored gloss in skin a little bit. Which is in contrast to the theory that a material is either dielectric or a metal. 

I even got more convinced when making a shader for fabric, there are some fabrics that appear quite metallic to me like Satin, some sports-wear, new carpets, and some more.  It feels like I can tell now how much of the rough colored gloss is present in a material like grass 5%, sand 10%, bricks 10%, satin 70%, skin 5%, some plastics 10% etc.  

But this is in contrast with that theory that a material is either dielectric or a metal. Any idea what I think I'm seeing then ?   

Maybe a theory is that for example in Satin, the light bounces in the grooves of the fabric, and this causes the reflections that reach my eye to now have some color influenced by the color of the fabric.

So I tried to simulate that in Blender:  A diffuse with a PBR reflection node (Cynicat Pro), and gave it Bump with a distorted wave texture with a very high scale (1000). The color of the gloss from the reflection node didn't change toward the color of the diffuse shader which was pink.

Then I tried to make the gloss more rough and that didn't work either. I tried that setup with 16 gloss bounces but that didn't have any effect.  

So I am a bit confused, I hope some one is able to clarify what I believe I'm seeing. I made a thread on BA as well
The theory I had seems to be correct: the light bounces in the ridges of the fabric and give the gloss a color toward the diffuse.  We cannot simulate this in blender with a bumpmap or a normalmap. So I did an experiment with real geometrie.  Here two illustrations. First illustration shows that we cannot achieve this with a bumpmap. Second illustration shows that we can achieve this in blender only with real geometrie and enough light bounces.