In my very short SL experience I found the mesh avatars, like Maitreya en Belleza and mesh heads like Lelutka, to be an absolute nightmare in most viewers.
Not only I but also the mesh avatars around me end up with body parts floating apart and face parts partially rendered. Forcing re-texturing or re-rendering doesn't help; changing drawing distance or texture detail will not help neither. Only the old Windows aproach works sometimes: close everything and startup again, and if that doesn't help restart again.
The classic avatar has a skirt problem: it uses transparency to shorten it and all viewers cannot handle overlayed transparency, so your skirt will cut holes in the floor or in the fog or in the water. I m still looking for a mini skirt, a short skirt and a midi skirt to use as glitch with flexi-prim skirts!