I found an odd quarter in my change dated 1967. Even though its worn like most circulated quarters from '67, the reeds on the edges are just as sharp as the day it was minted. Why would the reeds be so clean cut and sharp on a heavily worn quarter? Even a quarter from 2003 in EF-40 has duller edges. I don't see any modification to the coin, and the diameter is still the same.
I believe you're looking at a weakly struck coin from worn dies rather than a worn quarter. These are getting quite scarce in circulation in grades over F but there are still variety hunters who have no outlet for inferior coins and just spend them. There are a few of these that were saved and if a dealer gets a set in the shop he just might pop out everything that's junk for the cash register. The early clads were just horribly made. The coins in circulation aren't nearly as worn as they appear because they never had much detail to start with.
I often say that wear starts from the high points of a coin's surface and goes downward from there but this thread highlights something of an inaccuracy of this statement. It's all the leading surfaces including the edge that are first to suffer wear from collisions and abrasions. Collectors are merely in the habit of ignoring the edges but with clad there is more reason to pay attention to it. No doubt many newer states and parks collectors search for nice shiny edges to identify the newer issues and once in a long while are surprised to find that an eagle reverse quarter is in nice XF or better condition.
