Mirrors at home could be real trouble sometimes. Among the rest of the stuff you need to clean, in order to maintain clean level sufficient enough for regular household. One of the most common problems with mirrors, are the so called black spots. They could be caused by the cleaning product, if it has gotten behind the glass near the edge. Basically, it means that the back of the mirror is damaged. If you notice spots in the middle of the mirror, then that most likely is moisture. In those cases the damages are irreparable, but what you can do is to try cleaning them and preserve the mirror for longer and of course mask the spots as much, as possible.
