Well I can say this. Since out of the box (November 12th), I've been using my droid naked, just put it in my right leg pocket in my carpenter jeans. I also happen to work construction. In Florida. I don't care where you go in FL, there is sand, it's in contact with my phone constantly. I've worked months on beaches laying on the ground building pool decks exc... I work in the most dirty environments known to man. I've dropped my phone many times, dirt, gravel asphalt...wet from sweat and rain...I've impacted it in my pocket with hammers, drills, bolt cutters, materials from demolition...anything you can imagine and this phone and it's screen have withstood my every attempt to kill it.
I don't have a single scratch on my phone aside from on the metal corners from dropping it on asphalt and concrete. Not A single scratch. I do have a considerable amount of dust under the right top corner of the screen (as expected), but the glass it's self is perfect.
I've even had days at work where I go to open my keyboard and can't because so much material gets in the slider it won't move. I just tap the side with my hammer and jiggle it a bit till it slowly opens and then I just work it back and forth to remove the debris by crushing it into powder and wiping it away or sucking out the sand and concrete stuff from the speakers/slider with a vacuum.
I've got no idea what you all are doing to your screens but damn, if I can't hurt it from every day use in my everyday environment I can't imagine what it would take to cause this phone any harm...but I can promise that sand under normal circumstances (light friction) won't scratch this thing, it just doesn't happen or I'd know all too well by now.