I think that learning to dance is a lot like learning to drive a car with a manual transmission (stick shift). There is a certain amount of and intellectualism before you first try. Your mind intellectually understands that the clutch must be depressed to get the car in gear. But it is the repeat, repeat, repeat of hearing the gears grind that allows you finally get it in gear. I think toan-huong may be on to something with his idea that strong emotions help speed or imprint a learned behavior - in this case it is the loud, horrible and embarrassing sound of the gears grinding. If that doesn't motivate you to improve your shifting nothing will!! The fortunate thing in learning to drive a stick shift is that there is instant (and very negative) feedback if you do it wrong.
The concept of muscle memory I think is key. If you repeat any action over and over, you get to the point where you no longer have to think about it. It passes out of the realm of conscious control into the realm of unconscious muscle memory. In learning to shift, if you are having difficulty getting it correct, an explanation will point you in the right direction, but ultimately it is trial and error and repetition to the point where the damn gears stop making that awful noise. It takes no Einstein to learn stick shift - everyone eventually gets it, except those few who give up, concluding it is impossible for them to succeed (there is clear salsa implication here!)
With regard to dance, I am a person who learns much more effectively with a little explanation, repeat, repeat, repeat; a little more explanation, repeat, repeat, repeat; tweak this, repeat, repeat,repeat; tweak that repeat, repeat repeat. Lengthy explanations get in the way for me. Learn one thing well, then add another, then add another. But it is the practice, not the explanation that allows you to own it.
One main difference in learning to dance as compared to learning to shift is that the loud grinding noise does not exist in the dance
(with a few notable and memorable exceptions!!), so the problem in learning to dance is that it is up to the teacher, or ultimately the Universe, to point out when a dancer is not getting it as right as it could be. Mirrors can be a big help here, or self -videos, or RPFS (Repeated Pattern Failure Syndrome). A good teacher can instantly identify the point to be improved, and then has the tools in his or her teacher's toolbox - humor, pantomime, ability to demonstrate, skillful use of metaphors and imagery, the ability to relate to dancers' stages and anxieties - to get the job done. Because there are so many ways to teach, yes,it is very true that a good dancer does not necessarily a good teacher make. I tend to think a dancer who is of moderate skill but a great teacher trumps a dancer of great skill but of moderate teaching skill. At least for beginners and improvers.
Many people don't want to know how bad they are dancing, and like the Pope say, who are we to judge?
Ultimately it is the teacher's task to know the student well enough to know what it is they want to learn, and how much they are willing to pay for it (I'm not talking cash here). I think a lot of teachers neglect this important point and project their own expectations and definitions of "dancing good" and the mismatch between students' and teachers' expectations ends poorly.
Interesting thread, made me think. I'll sleep on it tonight.