So I have an early 2015 rMBP which I purchased a few months back, has had little use and is in very good condition... Now, In all the time I have had this machine only once have I needed to clean the screen. I had a small fingerprint in the corner a few weeks after purchase so I used the microfibre cloth (dry) which came with my rMPB. I always give the keyboard a wipe after use with a dry microfibre cloth ( courtesy of Specsavers ). After seeing the staingate threads and photos, I figure just in case right! Well this morning, not having used it for a week or so I open and find in the middle of the screen what appears to be a greasy imprint of some of the keys on the display! I won't lie, panic set in... This machine cost me £1400 or so! Having owned loads of laptops in the past which never needed babying I was thinking lots of nasty apple thoughts. I was going to grab my iPhone and take some photo's and post them here but thought hang on, calm down... I went and got the microfibre cloth (apple supplied one) and wet it with water (and only water), I wiped my screen in light and I mean very light circular motion and my screen is like new again. I can't believe it, thought I was screwed!