I don't know why but there are times when my desktop will look fuzzy as well as the icons on it. The panels are unaffected and so are the programs running, I will just see the fuzziness when I go to look at my desktop.
http://i.stack.imgur.com/vSuy4.png (here is the link to a screenshot of my desktop)
When I click the icons, their fuzziness goes away but the area around them is still the same. When I log out then login, everything is back to normal.
I am running Ubuntu 13.10 in xfce session.