Dunno. Can only trust my own measurements. I know I did them right, and I know that people as a whole are sloppy (You could say... Imprecise ) and OCNers as a whole are keen to find mouse problems.
This kind of inconsistent movement not only doesn't make sense to me in terms of sensor operation, it would be highly noticeable in game.
Draw your own conclusions, I'm not going to get mired deeper into a pointless argument over this.