The question is, how do you produce the bump maps?

If you use the diffuse map and make a bump from it, then you get a wrong bump map. A bump map should always be made from scratch. Most professionals begin with the bump map and then create a diffuse map.

Now you mention 3dream, and immediately with my pet peeve. He usesa lot of reflection and also oversharpened skin. This can cause problems with bump/normal maps if you create them from the diffuse map.

From what i can remember you own zbrush. I create my bumps and normals in zbrush, directly onto the model. This way the pores are the right size. It does not matter which program you use for rendering. it is all the same. Here is an example of my gen 8 character( have not one on hand from a poser render on the moment) where i applied that tecnique: