Let's call the drawing you're x-ref'ing 'Baseplan'. Let's call the drawing you're bringing the xref into 'A-1'. A-1 is the drawing that is opened.
Baseplan.dwg contains a layer called 'Walls' that has a continuous linetype and color 2.
A-1 has visretain set to "0" (off).
You change the layer 'Baseplan|Walls' to have a hidden linetype and color 8, save the drawing and reopen A-1.dwg
The walls are back to continuous and color 2.
Now you set visretain to "1" (on) and make the same changes, save and reopen A-1.dwg. Now the Walls layer stays the way you set it in A-1.dwg. However, no changes are being made to Baseplan.dwg.
Now, let's say you need all the original layer colors and linetypes back the way they are in Baseplan.dwg. Simply turn visretain off, save, reopen and viola! Back to the way the layers are in Baseplan.dwg.