But as has been said, it's much easier (and cheaper) to replace a screen protector... Also agree with a good silicone case being essential... and throw in a microfiber cleaning cloth too!
Originally Posted by DSperber
On my original J3 I thought that using a 100% cotton T-shirt as the cloth would be safe (after I breathed on the screen/protector). But as you said, surprisingly it is possible that you can still scuff and scratch the plastic protector sheet.
Fortunately, my original J3 had to be replaced by Cowon via RMA, and they sent me a second protector sheet. This time, I don't use a cotton rag to clean it. Instead, I use a micro-fiber lens cleaning cloth (spare, from eyeglasses) and am very careful not to rub to hard after breathing on the sheet before cleaning.
But you're right... it is possible to scuff the protector itself, if you abuse it while cleaning too hard and/or with the wrong cloth.