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 do both. Once or twice a week they get washed. But I never remember to bring a cloth with me, so if I’m out and about and get a smudge on my glasses, using my shirt is 1000% preferred over just leaving the smudge there.