Are your meshes made of tris or quads? Poser has problems with either long, thin tris or quads and they will self-shadow. You should avoid these in your meshes. Also, backfacing polys or colinear facets may cause blotches, as might concave facets.

Otherwise, Poser has no problem with tris OR quads (quads preferred tho), and it even handles ngons, as long as they're flat ;).

Laurie