Kitchen Towel - is a cheap paper product, usually with a reasonable content of raw wood fibres unaltered by the paper making process. And as such, will happily scratch plastic windows or spectacle lenses.
Real "optical cleaning paper" is vastly more expensive.
Probably the best thing is an old, well washed T-shirt - or similar piece of towelling. These should be super soft and have no nasties lying in wait.
Towelling also works really, really well when buffing off any wax you've used on a car or caravan...
Probably the most important tip is - anything cleaning cloth that you drop on the floor shouldn't be used to clean windows or buff a car - it's bound to have picked up grit...
Robert