When I moved house, about 4 years ago (to a part of Ireland with an even wetter climate) I decided to clean it. I took out the front element and cleaned it with water and polished it gently with a cloth and put it back.
Yes... It is an absolute priority to prevent cleaning marks while hard particles can be still there. Most of dust found indoors is soft, but not always. Main hazard are the hard dust particles like those blowed by wind, it can be sand !!
Always we can leave some finger print by accident, this requires soap... also first wash should be wet for the case a hard particle is still there. Personally I use a single drop of concentrated dish washing detergent in 100ml bidistilled water my be enough for the "first bath", wipping gently the wet surface . Depending on the soap brand one has to add a bit more or less, just add enough to perceive the tensioactive effect, when the "drops"on glas disapear to form a liquid layer then the soap amount is good.
For the "second bath" I use simple bidistilled water to remove any detergent, I wipe the remaining bidistilled water drops with a microfiber mini towell, those for eye glasses, just removing the drops with near no friction. No drying mark should remain. If we use some alcohol we usually have some residue that has to be removed with a dry cloth, this may be risky if the cloth has some particle.
I use my HEPA air purifier (Honeywell HAP-16200E) to clean the room air, like I do when scanning, drying or handling negatives.
To me, bidistilled water is a key factor, I tried several kinds of alcohols and specialized products but at the end the simple thing is what liked me: a drop of soap, and high purity water.
