While it means polygon count may be higher, it is pretty much always possible to avoid triangles if you are careful.  Take a look at that toplogy guide:
http://megamorph.gigacities.net/TopologyGuide/TopologyGuide.htm

Although Poser doesn't really have a lot of problems with triangles, they tend to be easier to UVmap and to get more predictable deformations when animating - triangles cannot flex, but quads can flex as if they were cut diagonally both ways (which they are, internally).

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