I recently dropped something on my Nook Simple Touch with Glowlight and created a "hole" in the light guide layer
. I have found a way to minimize this distraction and thought I would share it here. I have my Nook rooted and have AIReader installed. I noticed that if I use white text on a black background the "hole" in the light guide is much less distracting. It seems the bright spot from the "hole" appears much smaller when the light does not reflect off of a white background. With the Glowlight off the defect it not noticeable, so reading in normal light is fine and when I have the Glowlight on switching to the black background doesn't seem so strange because the room is dark anyway.
I suspect others have this all too common problem, so I hope this information helps someone.