nice comments, thank you.
So what's wrong with the right arm? My first idea was that the sky is reflecting in the skin - I have added a reflective shader with ray traces reflections on the skin shader. But after some testrenders I found that the color on the arm is correct - all other parts are to bright and red
The color of the sand is done with two Power Fractal shader (yellow-orange-red) on the color input of a default shader, and the Diffuse colo(u)r was set to white (1). This was too much so the GI tinted the objects - except the parts that are facing up.
Anyway, this was only to test a sand shader with real world scaling.
