Before you lift that spray bottle to spritz your mirror with glass cleaner, think again. Instead of spraying the cleaner directly on the mirror, you should be spraying the paper towel or newspaper you’re using to clean it instead. Why? Because the cleaner that drips down the mirror can seep into the crevices and cause black spots to form on the reflective surface.
And if you end up with streaks on your mirror, use a microfiber cloth or a coffee filter to buff them out.