I have been using a shaggymac for a while now to protect the screen from the metal keyboard on my macbook pro. I have always noticed dirt and dust on the screen and have wondered if the screen protecter is more damaging than it is worth. I wash it regularly but I imagine it is a good collector of dirt and dust. It is damaging to put this in between the keyboard and screen? What do these things actually do anyways. Has anyone wished they had bought one because of damage?