Great!
My figure skating director basically agrees. She says spins, like a lot of skating, are not specific in terms of what part of the blade you use, or the exact body position. Which explains why coaches differ so much in what they teach. Of course some moves (like jumps) are specific as to inside and outside edges. But she says it is now OK to spin on inside edges, not just outside too.
But if things are so non-specific, it is not surprising to me that judges don't always agree.
I guess the "scratch spin" is called an "upright spin" (with a forwards entry?) by USFigureSkating...
I guess a reasonable way to see possible variations is to look online for videos from expert skaters and coaches.
E.g., here is a video of Karen Courtland Kelly. Her take is that (for scratch spins) you should stay off the toepick as much as possible (i.e., she treats it as a blur spin), and gives other tips about it. E.g., she says the exact body position is not well defined.
Karen Courtland Kelly breaks down the keys to a good scratch spin and why she feels the name of the spin is confusing.
www.facebook.com
Reflecting these ideas, she says the "forward scratch spin" should more accurately be called a "backwards inside blur spin". She shows multiple entries, as well as doing a change foot to a backspin.
She comes across as so happy and enthusiastic!
I can't see the "members only" portion of the USFigureSkating.org website, because I no longer belong. (I would have to rejoin, if I wanted to test with them). E.g.,
https://www.usfigureskating.org/sites/default/files/media-files/Coaches to Test Judges FAQ.pdf
is
"Singles/Pairs Manual for Test Judges"
Maybe it has more information on how spins are marked, that goes beyond the very non-specific info in the Rulebook, which is mostly just a copy of what the ISU Singles & pairs document says. Or maybe not.
And I suppose other non-U.S. national websites might be searched too.