1964 Nickel With A Counterclockwise Rev

Rotated reverses on modern coins are scarce. On large cents, they're almost the rule.

All depends, how much rotation is there? 15 degrees either way is within mint tolerances. By picturing it the way you did there is no way to tell how uch it is rotated.

From that much rotation on a modern coin I'm a little surprized that it wasn't noted on the slab. Rotated reverses are seldom even noticed on coins until they are put into an album, slab or 2x2. They are so seldom even mentioned that many books on errors do not mention them. For example the Red Book, pages 401 to 404 has no mention of them. Other books and web sites such as coppercoins.com also make no mention of rotated reverses unless I missed it somewhere. The Lincoln Cent Resourse web site does cover rotated reverses though.
In my experience Mercury dimes probably have the greatest amount of rotated reverses. I have well over 3,000 Mercury dimes and would be willing to speculate that about 20% or more have some type of rotated reverses. I've found it odd though that the majority of rotated reverses are to the right on Mercury dimes.
I would think that since yours is not as common it would bring somewhat of a premium at a coin show where error collectors are a little more common also.
Here is just one more thing I've always wondered about. Is it the reverse that is rotated or the obverse?

Thanks Carl & Metal man I sent 14 modern coin in for the $8.00 per coin with 2 of the 14 free. that maybe why it wasn't noted. Details were extra $12.00

Guess that is true. It's amazing that such rotations go unnoticed until the coin is actually looked at for such a rotation. Ecven in a 2x2 it goes unnoticed. I think the first time I ever noticed a reverse rotation was in the Whitman Albums where you can see both sides. Everyone lines up the fronts and when you turn the page the reverse make you think your drunk sometimes. Really true of Mercury dimes. Probably why as noted it's really the obverse that is rotated but who notices.