I have an Epson Perfection V500 Photo flatbed scanner. Tiny particles of dust always seem to land on the glass no matter what. Seems that this is a common thing with our present Texas environment and not just in my room or yours.
For cleaning the glass, I use Pearle Vision's Lens Cleaner and clean cotton cloth handkerchiefs found at Wal Mart. The lower-priced lens cleaners found in pharmacies don't seem to do well. Pearle Vision's Lens Cleaner does not seem to attract dust like what I used previously.
The outside side of the glass is easy, but you might want to consider checking the inside side of the glass. It may be that the dust is on the inside.
Last year, I noticed that the glass had a rainbow-colored haze on the inside side of the glass. I observed this haze upon immediate power up of the scanner while the lid was up. Did the factory assembly personnel not notice the haze, or did it develop over time? I don't know how it got there.
After much reading on the Internet and with an expired warranty plus a few brewskies to settle the nerves, I took it apart carefully. The glass was placed on a clean towel and wiped on both sides. Holding it up to the sun verified when I could stop buffing with clean hankies. Reassembly and all is well but the dust never goes away.
Before laying down anything on the scanner, I now give the glass and whatever I am scanning a few blasts from a
Giottos Rocket Air Blower - (Large) 7.5" AA1900 B&H Photo . So far, so good.
I hope that this helps.