When I'm just sitting here and typing on the forums? ( and it's on the outside?)
Also, without realizing it, you're probably rubbing your eyes or around your eyes & touching the glass at the same time.
I buy the Walgreen's brand eyeglass cleaner & it works great. I keep that handy. It works better than water.
(I couldn't sleep so I thought I'd turn on the TV & get on my laptop til I felt sleepy again. That's why I'm posting so late.)