"Graciousness"

You would think that looking down is enough to signal that you do not want to dance just then but sometimes the culture of a particular milonga is such that it can be thought by some acceptable or not uncommon to invite a woman by walking up. Sometimes poor seating without clear lines of sight, or poor lighting provoke the same.  

I was mortified recently.  Before the práctica I had arranged with an experienced dancer to help her practice "leading".  Between hosting, DJing, dancing with beginners and, if I'm lucky, a tanda or two with my favourite dancers I don't have a lot of time; besides, when I can dance is determined by the music appropriate to the different dancers.  So I found myself with a free moment and went up to her to see if she wanted to do her leading.  Despite our arrangement, she was clearly taken aback.  This isn't a mistake I will make again.

When (usually a guy) walks up, some think "presumably the woman will be gracious enough not to refuse".  Older people often tell you that was the English way, at say, dances in the 50s. But a man who has cornered a woman between obligation and embarrassment is hardly giving her a choice. He is presuming she wants to dance with him. In the worst cases she is manipulated into thinking she must want to dance with him because despite her instincts, she somehow does not refuse. Why doesn't she refuse? She doesn't want to appear impolite.  The guy bets on, capitalises on, takes advantages of exactly that.  That's manipulation.

Men sometimes graciously dance with women who mistakenly think they have been invited by look, when in fact the guy was inviting the woman in front of her. Usually, he will dance first with his intended partner and then with the woman who thought she was being invited. So why shouldn't women be similarly "gracious"? But that is like comparing apples with oranges. Besides, as a guy once put it to me, "most women are embraceable". The same is not necessarily true the other way around.