Posted 08 January 2013 - 12:15 PM
There is such a thing called glass cancer, I think this maybe what your facing.
Glass is porous, cleaning products damage glass, so does calcium in water.
I think you will find that the glass is damaged, don't dispair, a way to tell in put a bit of oil on a cloth, paper towel, tissue or whatever and put it on the glass, use a lot if need be in a small area. If the glass clears up in that spot, you know it's glass cancer. It just means there are little holes in the glasses surface, not amount of cleaning will fix it - apparently if you use almond oil, this is a temporary solution. It won't fix it, but if you do it before you move, it will look good, and you won't have to replace it.
Google glass cancer. Hope this helps