I'm mostly just guessing, but -
I would think that any 1 series body will have been used by either a pro who used the **** out of it, or a hobbyist who didn't put much wear & tear on it. The difference between those two bodies ought to be easy to spot, and should be reflected in the condition rating...
I don't really see there being much middle ground on pro bodies...
Working pros, or hobbyists with large budgets...
They are nice though... I use a 1N RS (film), and after using that, I don't think I can go back to anything less than another 1 series body... My next digital body will most likely be a used 1 series 1 or 2 generations behind the current one (whenever I buy it).