I don't use glass cleaner. Most of those have ammonia, which is way too strong of a chemical to be cleaning my expensive subs with.

What I do is disconnect everything and use a dry microfiber cloth. If something is truly dirty, I will use a drop or two of a non-residue leaving detergent (like Ivory) in some water to wipe it down, then go over that with another cloth with just plain water just to make sure, then dry it with the micofiber.

Hope that helps.