Bright marks appearing on the cigars can basically have two causes. If the marks are light gray in color, dusty and can be easily wiped off with a cloth, then the spots are only a result of the normal aging process of the cigars, which does not impair the taste of the cigars.
If however the spots are crusty and blue-green in color then the cigars are infected by mold. Mold may form if cigars are stored at excessively high humidity levels. In such cases the infected cigars must be removed and the humidor should be cleaned carefully with a dry cloth. The humidifier should be cleaned carefully with warm water and if there is mold on the humidifier, the humidifier should be replaced. Under no circumstances should the infected cigars be put back into the clean humidor.