Lens manufacturers say that anything other than a microfiber cloth will damage the coatings on a lens. But microfiber cloths eventually pick up crap and they look like they're a pain to wash.
How do you keep your lenses clean? Are you using cloth/kleenex or microfiber cloths? If you use microfiber cloths, how do you clean those?
I use the edge of my shirt, or whatever I happen to be wearing. I never use any sort of soap or cleaning solution. Works fine. My specs last longer than it takes until I need to get a new prescription anyway.