As onpon has mentioned, smoothing the tip of the stylus ....
....I recall someone else [though may have been you before too onpon?] mentioning a while back about this.
They found that the official stylus was a bit 'scratchy' at the tip and they had sanded it down a little to make it more smooth.
Perhaps those getting light scratches have these old stylus, if you look real close at the tip you may see a tiny rough bit of plastic sticking out, causing the scratches.
Edit: It was Sigma, as per this post:
http://boards.openpa...aper#entry18655 .. slightly dif issue as that was regarding it getting jammed in the slot, but that is what I was thinking of.
Might still just be some of these stylus' [styli?] have a rough bit on the top