i can't see it, but mine got a few spots on the screen that makes me cringe when i drag the stylus over

Any idea, if there is any thicker point stylus available?

would using the other end of the stylus work or would it be too imprecise or still too rough?

That seems a bit thicker -> http://en.wikipedia.org/wiki/File:Nokia770-fi-wiki.jpg

I wouldn't recommend the backend might scratch your screen even more.

Yeah you can, it's quite easy when you know the proper method.

You don't really need a 'clean room' like environment, though that would certainly help a small bit.

Most screen guards are sandwiched between two outer protective layers. They serve an important purpose.

You have your nice shiny new screen guard in one hand, dusted up N900 in the other.

First give your N900 screen a really good clean with one of those 3M cloths, make sure you have no oil or finger prints. Don't worry about tiny bits of dust just yet though.

Next, peel off the TOP layer of the screen guard. Do not peel off the bottom sheet.

With the TOP layer in hand, stick it on your screen as if it was the actual screen guard itself - position it in the same way, try to do it without getting bubbles, then peel it off. Do this a few times. Why? It picks up all the tiny bits of dust. That is its purpose in life.

Next, fairly quickly, grab the other two sheets - don't just peel them apart though - start at the bottom or top and peel just a little bit, stick the peeled guard end on the screen and slowly pull the bottom sheet away while gently sticking the guard down - normally you can actually do this with no bubbles forming at all, but if you do get some - most screen guards have a small plastic scraper thing included - use to push the bubbles out.

Easy. Job done. : )