I may have mentioned this a couple times before, but the spiral is one of my favorite elements. What, you ask...? It is only the skater traveling in a static pose with one leg up behind her -- what could be difficult or interesting about that?
Well to me the spiral encapsulates all three of my top skating criteria in a simple to judge move: grace, balance, and skill. Also since I have a skating daughter I recognize how difficult it is to accomplish a quality spiral, mainly since I have had the privilege of witnessing all the young skaters attempt this as they were growing up through their coaching sessions.
The first challenge is bringing your trailing leg up at a smooth consistent speed and then stopping at the correct height. Go too far and you faceplant. Don't go far enough and it's impossible to hold. Viewing a gal practice this is like observing a young person learn how to do a headstand. Trial and error, muscle memory, finding the balance points.
Once you're pegged into position you get to deal with the vagaries of blades and bumps in the ice. I don't know from experience but it seems to me from watching that the gals that maintain the most velocity in their spiral have an easier time keeping their position fixed as they traverse the rink's incongruities. Those traveling slowly get whomped by every small dent and surface gash.
What I actually focus on after examining the smoothness of entry is your skates: my peripheral vision makes sure the hind leg stays frozen exactly at the same height, and my wandering eyes appreciate any stylistic hand movements, but mostly I am examining if your edges stay clean and committed as you manage the traversal. I am watching how you finesse the minuscule velocity changes imposed by the bumpy ice with your core muscles.
Holding your rear leg stock still is enough of a challenge, but if you can do this while also throwing in some slight balletic arm movements at the same time, I'm doubly impressed.
The other notable oddity about this element is, of course, your face is presented statically straight up toward the audience (or judges, depending on your angle). Please don't skate your spiral with your mouth open.
Somewhat miraculously this element also critically narrows the body types for those who willl eventually become the great skaters. Obviously you need strong glutes to pull it off well, but additionally if your center of gravity stays fixed as you tilt into position then this indicates that your top and bottom halves are appropriately balanced.