My skins often show as up very low res and happens randomly.

[Mother Ruska]

so my av skins and sometimes clothing layers randomly go low res. when this happens i can change the skin or an article of clothing or sometimes an alpha layer and it rarely get's better, but this isn't a guarantee that things will get better. rebake doesn't seem to help either. 

[MartinRJ Fayray]

Hello,

when that happens just remember the keyboard shortcut CTRL+ALT+R to fix your clothing and skin layers.

This is known as 'rebake' (your skin and clothing layer textures will be merged by your viewer, and uploaded to the Second Life server).

The menu option is in the advanced menu -> "Rebake Textures". http://wiki.secondlife.com/wiki/Advanced_menu