As I learned more about optics, I was surprised to learn that a typical small scratch does not adversely impact image quality or resolution to any noticeable degree - depending on where the scratch resides on the lens. The same can be said for dust and dirt - the coverage has to be pretty bad and ugly before it really starts to send the image downhill. Eventually I did learn to just leave my optics alone and not worry about the tiny smudges or motes of dust - it's better to have a lens that looks a little dirty than have a lens that is scratched up from ill-advised attempts at cleaning.