You know what's annoying. Broken seals on double or triple paned windows. They cause a build up of moisture in between the glass, that neither you nor I can get to. And the problem is that when moisture or humidity builds up inside the glass, it becomes foggy and prevents you from getting those clear views that we often enjoy from clean windows. 

Most modern windows are created out of two pieces of glass with dead space in the middle that insulates your home. The glass's edge is sealed with caulking that keep out any moisture, and often times the interior of the pane is filled with an inert gas that acts as "insulation". When this rubber breaks, you oftentimes end up with dirty windows AND the gas inside escapes, meaning your windows won't keep your home as warm or cold as they should.