The way it works is that only the art that is on the server and is specified for use with certain models in-game shows up universally on all clients. If you made a client-side skin mod, like altering colors or adding detail or changing a texture file completely, it's only visible to you, and those you manually give you altered files to.
Altering PlaneShift art technically should not be done - if anyone wants to create a skin, they should do so from scratch - but there's usually no harm to it unless you do something stupid or outrageous :}