You can’t see how good someone is, but I think you can see how bad they are. I.e someone leading entirely with arms, no leg drive in any of their steps, hunched posture, no disassociation, etc.
For sure.
I think the sort of people we are here – willing to burn endless electrons discussing every aspect of tango to death – take "stands tall, pushes off the floor, leads with full-body spirals and never just the arms" and similar things as a baseline. Not having all of that and much more would be an instant deal-breaker for any teacher and probably for most potential dance partners. As you imply, "good" builds on top of that, and mostly in ways that you cannot see, at least not in the way you can see "bad."
My standards are something like:
Very Bad: Guilty of more than two or three of staring at partner, head tilt, no top-to-bottom body spiral in circular movements, pure arm-leading, pulling, pushing, hanging, hunching, forward collapse (no back activation), back lean (other than maybe in certain colgadas, but even then), always rocking back before stepping, no floor push, always dancing on tiptoes (never using the full foot), stepping from the knee down (or, really, from anywhere below the top of the buttocks), stiff legs (no knee softness or bend), linear steps across partner's lines when curved steps around partner's body would better maintain distance, wobbling when on one leg (leading to emergency touchdowns of the free foot), and a few other things. Or guilty of even one of those things to such a degree that the dance is difficult or painful regardless of all the rest!
Bad: Consistently guilty of one or two of the things under Very Bad, but not to such an extent that the dance is difficult or painful – it's merely not fun.
Average: Doesn't consistently do any of the things under Very Bad, but might backslide on bad days, when jostled by another couple, or otherwise not at 100%. Even then, errors don't manifest intensely enough to ruin the dance, and might even provoke a laugh.
Good: As Average, but when you dance with them, they exhibit a few of a comfortable embrace, instant initial connection, no loss of ongoing connection, intention toward you in all movements (so you know where all of their body parts are at all times), ability to generate 100% of their own momentum without donations, musicality, interesting (counter-)proposals, ability to shift axis (on/off, shared/individual), no loss of technique across a good-sized vocabulary, ability to send and receive micro-movements (even just breathing), and a few other things.
Very Good: Most or all of the stuff under Good – or a small subset of the things under Good to such a high degree that you don't even notice the things that they don't have!
I put myself at Average, with perhaps
slightly more Good days than Bad ones. My partners may disagree! But I don't think that from the outside, anybody can tell whether I'm Average, Good, or Very Good, only that I'm not Bad or Very Bad (I hope!).
—
Floorcraft sits outside this, because it's so damned controversial. For leaders, I'd have a separate scale similar to the above for it and rate them at the lower of the above scale and the floorcraft scale. I'm currently in a debate about this with some leaders I know personally, who feel that floorcraft isn't organic to the dance and represents not "being a better dancer" but "being better at sacrificing creativity for social acceptance." I disagree, but the existence of debate leads me to make this note.
