you're a troll. i don't believe for a second that you even HAVE a n1. iyou stated in numerous other threads how you had an iphone that you wouldn't give up.
i had two blackberrys, a 83xx and a Javelin, obv used the trackball extensively on both. the trackball itself had issues. it would get gunked up the way that old mice would, and require that i take it apart and clean it, and the stuff that i would pull out was NASTY. just gobs of the crap that you don't realize is all over your fingers. in spite of this, i NEVER had any dust under my screens in EITHER blackberry.
until you show us DOCUMENTED EVIDENCE from a REPUTABLE SOURCE showing that someone has PROVEN that that is how the dust particles are entering. this doesn't mean some other person posted a blog about it, or you saw it in a thread on another forum. reputable means engadget, phonescoop, slashdot, or hell, maybe you can dig up a watermarked inter-company memo from google to HTC. your theory is just that, a theory, and honestly, not a very good one at that, given that unlike the blackberrys, the trackball isn't located within the glass housing, and dust wouldn't have a direct route up to the screen from there.
until you can offer up something other than your good word, which via a forum where you've been trolling around harrassing people and acting like you know about a phone that you don't even own means nothing, your arguments hold no water here unless you can put something real behind them.