Hello, sorry, coming in late for this thread.

Some of the native Poser stuff has the smoothing problem as well, just load the
"Dresser" prop from "The Pad" of Poser 7 content and turn on smoothing. It looks
like exploding.

The way I get around that which helps in most cases is to load the props into blender,
and apply a modifier "EdgeSplit". As long as you do not press the "Apply" button,
your original geometry will stay low-poly. For .obj export, there is an option to apply
this on the fly during export. Please see attached image.

When you export multiple objects into one .obj file, Poser will load them into a single prop.
The "Edgesplit" can be applied to objects in Poser selectively (or even to selected "sharp"
edges only). This way you have great control on where this is applied and can keep smooth
object parts as well as sharp edges.

Hope this helps,
   Michael