Cleaning a black bathroom mirror is not as easy as it seems. You need to use a cleaner that is safe for the mirror in order to avoid damaging it. A common way of cleaning a black bathroom mirror is with a mixture of vinegar and water. This mixture will remove the dirt from the mirror, but will also leave behind streaks and residue that can be easily removed with a cloth or paper towel. The best way to clean your bathroom mirrors is to use an anti-static brush, which will remove the dirt without leaving behind streaks or residue.