What scares me the most is that many people carry lens cleaning supplies directly in their pants pocket, camera bags, or in any place they can find. They take it out and wipe the lens... Yikes! I keep mine in a clean zip lock bag that is replaced often. My cloths gets washed and cleaned often. I actually never had problems, and I am VERY particular about my lenses.
I have tried paper kind (also kept in plastic bags). I never liked these as they are not as absorbent and often leave smear marks. They seem to cause more scratches by minute grit based on my experience with eye glass lenses. I don't use them anymore.