Respectfully, now that a verdict has been rendered, Liberty Seated Dime, regular strikes, 1866-S PCGS [4644]? MS-62, which they describe in their latest bi-monthly Rare Coin Market Report as: "will have no wear on high points. There may be considerable marks and abrasions and some may be severe. Some may not be full and eye appeal may be negative. Luster may be dull," I am inclined to concur with the grading decision but continue to be puzzled by a Mint State scale that suggests something akin to Not Pregnant and Full-term Pregnancy, with gradations (based on months along in pregnancy) in between.
In all fairness, if grading could be done through the virtual submission of photographed examples, in-hand grading could be dispensed with. The Report suggests an actual retail price of $5,000.-$6500. Any discussion as to whether the coin appears to have been circulated would be an academic exercise. I agree with your concerns and, quite frankly, am puzzled as to how a coin struck as a circulation strike, for release into circulation, can attain Uncirculated, Mint State status.