I have noticed the same issue with Poser shaders, mostly V3 and V4 shaders but sometimes clothing item shaders as well.  I just hiighlight and select the "model" under V4 and then go to the shader room.  on th ebottom left it lists all of the shaders for the character.  Open them up one at a time by double clicking and lower their reflection and highlight settings, as well as shininess settings, to a value you like.  Do the same for each of the shaders that are for normal skin.  Don't do it for eye shaders or mouth shaders.  Hope this helps.

 

 

Rich