I just remembered I did recently ask someone to teach me a dance ("just off" the social floor), but 1) it was in a crowded bar just off the dance floor so it's less in the way than the onlookers 2) it is a notoriously easy dance 3) she knew I was good at dance 4) I picked it up in 45 seconds 5) we immediately went on to the dance floor and finished the song together with no further instruction.

So there are exceptions to the rule