I would have paid the same money for that coin as a 65 or 66. Normally, grade determines monetary value, along with eye appeal. In this case, I believe that eye appeal is so dominant, any good MS grade would have brought in a good price for what is otherwise, a very common date coin.
I did not even look at the price guides since it was fairly irrelevant on a common date coin with high end color. I did go and look it up now in the PCGS guide: it shows $25/$32/$42 for 64/65/66. What’s the difference between paying a premium above $32 vs above $42? I would concede the point if it was graded MS 68 (guide of $7,850) but really should have been graded 67 (guide of $200). Paying a premium above the 68 guide would have been a double bump.
I was going to guess MS65 due to the hits on Washingtons head, but I guess PCGS gave it a bump (and rightfully so) for the massive eye appeal.
Yes there is market grading involved (although that brings up the debate of whether or not CAC is also approving a market grade) but with the value spread of 65 to 66 being $10, there isn't much of a difference given that the toning premium is multiples of that.
My personal opinion is market grading makes more of a difference with coins that are generally older series. Moderns that are very close in price in most MS grades, such as Washington Quarters are influenced more by eye appeal. The toning premium on this coin is huge, whereas one has to get to MS 67 or higher to get big price jumps on this Washington. I’ve sold common date Morgans with huge toning premiums, if the toning was unusually beautiful. Some of the very common S and O mint Morgans produce beautiful toned coins that sell for big money, irrespective of whether they were MS 63, 64, or 65. It takes a very high grade common date coin, such as a 67-68 to get a coin that is wildly expensive based on grade (except for conditional rarities).
I don’t know that you boys are getting what PCGS thinks its grades mean. It thinks they mean the grades the coins should trade for in the market. That’d presumably mean a PCGS66, as here, should sell for 66 money in their price guide. It wouldn’t sell for 67 money for superior toning, because the toning was already factored into the market grade PCGS gave it. PCGS’s grades are tied to their price guide, as their price guide is what PCGS is saying their coins should trade for in the market. As such, should this coin trade for much higher for the toning, there’s no way around it, PCGS got the market grade low. That’s why I gave it a PCGS67, I believe it will trade for that money in the market.
I think you're right when you suggest they don't account for spectacular toning in their market grades and price guide.