Models need volume.  Imagine that.  GI (global illumination), IDL, whatever you want to call it these days, never really worked well with single-sided faces in any software application, without some material workaround.  In fact, refractions often require tweaking if there's no actual object thickness too, because IOR values depend on volume.  Some physically based light scattering algorythms are the same way.  It's the fact that we're trying to make real world calculations of light and physics on "single-sided" impossible objects.  Give them volume, and the results will work better.  Modelling objects for Poser has always been virtual.  People depended heavily on just textures.  Now we're starting to incorporate physics into the process more than ever, in our lighting and materials, so models will need to accomidate.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.