Its not so much you sounding like a jerk, its that fact that your first word in your post was "WRONG", literally. Starting your post like that is very confrontational, and is likely to piss off alot of people. A more diplomatic approach would have been more appropriate. Such as "you not exactely right there". You have to learn to be diplomatic in posts, and try to see all sides of a opinion. For example, when i put "Its your opinion on the mouse, but i, as well as alot of people on the forums will dissagree with you quite badly", its a more diplomatic approach, and prevents to an extent a backlash of words from whoever your talking to. Having said that though, if i feel very strongly about something, then every once in a while, i tend to "lash out" like that. Dont worry about it.
Im assuming that the MX500 used the same paint as the MX700, and the paint on my MX700 has`nt come off yet.
As for your curser shaking, you might have a bad model.
Was the surfaces that you were using the MX500 on shiny? or slightly shiny? Cos if i use my MX700 on even a slightly shiny surface, becuase of the way the sensoe on it works, the curser jumps around and shakes a bit. But on normal surfaces, its fine.