The problem with the cabeceo is that if there is a line of girls sitting together, it's hard for them to tell who the man is looking at. My brilliant DH came up with the perfect solution. Follow these easy steps:
1. Walk down the line of ladies.
2. Place your hand on each lady's head. If you are not asking her to dance, say "duck".
3. When you get to the one you want to dance with, say, "Goose" and do the cabeceo.
This will leave no doubt in anyone's mind who you are addressing.
Seriously, though, it is an issue. When you use the cabeceo, even though you think you have a good eyelock with the person you're inviting, the girls on either side of her might think you're looking at them. If there's any doubt, extend a hand or walk closer so the wrong girl doesn't jump up to dance with you and faces embarrassment when she realizes she's wrong! Please...the followers of the world will thank you.
I have to say, I'm divided on whether I like the cabeceo or not. I think it has its uses, but there is the problem I described above. Additionally, if a girl isn't paying attention or is just too shy to stare at every man in sight, she might miss out on some good dances. On the other hand, it's a good way to avoid being asked to dance by someone you don't want to dance with, because you can just studiously not look at them. For people who insist that it's the only way to invite someone to dance because it's traditional...well, I think that's a little silly. If it works for you and the situation, use it. But if you prefer to just say, "Hey, wanna dance?" I say go for it.
Of course, I've only been dancing Tango for two months, so you can pshaw if you like, but in 15 years of ballroom and swing dancing where most people just ask, I just don't see why some people are so rabid about using cabeceo. Some people in those circles use it without knowing it has a name or tradition. Perhaps in Argentina it's a vital part of the way men and women relate to each other in all situations, but America is different.
Plus, I'm at the point where if I decide to be brave and ask a man to dance, unless he's a friend I feel very awkward using the cabeceo. It implies a level of competence...like, "surely, you want to dance with me, and now I am allowing you to." This is not something I can comfortably do with men I dance with often, but I can't bring myself to do it with a stranger or someone better than me.