Isn't what is toning the coin already on the coin? Toning can't be completely stopped can it (at least practically from a cost stand point)?
You would be incorrect in that assumption. Toning is the effect of thin film interference on a coin and that is, for the most part, a gas phase interaction between the local environment and the surface of the coin. Therefore, take the coin away from the local environment and you can stop toning, for all practical purposes, completely.
For my collection, eye appeal means more to me than does grading. I have owned MS66 silver dollars that were not what I would consider pretty coins, and I have some AU eye candy that I will keep as long as I'm still in the hobby. Currently, I buy both toned and untoned coins as long as they pass the eye test.
It depends on what one admires, right? One admires grades, looks are secondary. One admires looks, grades are secondary. To admire grades, one has to study. To admire looks, one has to look. In a nut...
What I think is that the toned coins look very nice. So do the bright white coins. But at least with the white ones you can have a better idea of the value. With the toned ones it's crap shoot. You might pay 25x over book but you have to hope if you ever sell that someone is willing to pay the same price.
I don't buy toners to flip them but to keep them. You're right, if you pay far over book it'll be hard to sell them again for that price. But nicely toned coins are not always way over book, especially toned Morgans are often quite reasonably priced.
For certified coins, study takes a siesta; however, for ungraded coins you are 100% correct. Of course higher graded coins generally have better strikes and less unsightly marks, but not all coins with the same grade look equal, so even those that admire grades still make choices based on eye appeal.
@Jason Hoffpauir , thanks! That was my first big premium coin. I was a little nervous paying that much for the coin, but I'm so glad I did. It's that "end roll" toning. The dark blue around the rims is a nice accent to the coppery toning which covers the majority of the coin.