When the current avatar was made the Lindens were optimizing for performance. This meant they took some crafty shortcuts to save download and CPU time. One of those crafty design features creates some strange behavior with the Second Life™ avatar’s UVMap and how the viewer handles it.
Gaia Clary of Machinimatrix.org has figured out what is going on and how to compensate for it.
To understand the problem and how to work around it check out the video that Gaia made.
The problem is complex. Solving it allows one to make better looking skins and system clothes. Understanding what is happening allows one to make better mesh clothes.
Drop by the SL Forum and thank Gaia for this video and figuring out how the UVMap is being maniplulated. Improve UVs for SL compatible meshes.
Obviously making mesh clothes is complex. As time has passed we have learned how complex it is. That makes for a very steep learning curve. Perhaps while the Lindens are talking about Liquid Mesh they could say a word or two about how to make things easier for new clothes makers.