I just noticed that the walls above my diffusers have a greasy area about 2 feet by 1 foot wide. I have been using them for about eight months and never noticed it before. I caught the light just right near one of them and there it was. This big grease stain. I checked the other one and found the same thing. Has any one else noticed this and if so how do I get it off the wall. I might stop using the diffusers now that I know they do this.
