Re: 2004 with 583 miles for sale on ebay.
Reasons for people doing things like this are myriad. Bought by someone wealthy it may have simply been forgotten or driven for a week or two, found uncomfortable, and just left in a garage for the next decade.
Most common reason for selling on the open market: "estate sales" with "bankruptcy" and "divorce" right up there.
Heck I've seen cars (usually halo cars) decades later that still have the MCO. (Driven only on dealer plates)
Is not common but not that unusual either.
That said there are a lot of things that just fail with age (and I have cleaned out some really nasty gas tanks) and not milage.