I had hit and miss with eye glasses cleaners but once I found one that works well - meaning cleans well and leaves no residues, that's what I stick with. I also use microfiber cloth originally made for eye glasses applications. I keep mine clean though. They live in zip lock bags. I never just toss them in my camera bag or pocket. My "stash" is also in a plastic bag. If any of them get visibly soiled, they are tossed away. Otherwise, they go into a laundry bag and washed.