I have to say, I find this *highly* impossible. I was the same way, I put my phone in my pocket with nothing else, nothing ever goes into the same pocket as my phone. Lo and behold, iPhone 5 has tiny micro scratches after a few weeks, iPhone 6+ and my brother iPhone 6, same thing.
They're not easy to see as with a deep or long scratch. But I guarantee you, if you look at your screen at the right angle under a light, you will see all the scratches which you think do not exist. It's unfortunate, especially since I use my phone without a case or screen protector, but I've accepted the micro scratches issue.
Clearly, I'm not very worried about re-sale value as I like to use my things as they are meant to be used. I take care of my stuff, but I'm not going to go above and beyond to protect it like it's some borrowed item that needs to be returned in mint condition.