I've got an x demo and its perfect - not one single tiny mark on it whatsoever. Also, as soon as you take the lens off any digital camera dust will bite - if not on the first occassion then the next.
I got mine from Ffordes - it was exactly as described, and I'm so glad I saved the money because it enabled me to buy the lens I wanted.
It does depend on your stance on these things, but seeing as so many people on here have moaned that their BRAND NEW ones have been faulty I could argue that a demo model would be safer because they wouldn't want to be showing off a camear with faults.
I don't think that cars need to be run in the same as they used to be - times have changed