The problem the OP faced was that people at the conference were generally sorting people into the general categories of "technical and worth talking to" or "just trying to sell me something" and would make the Bayesian inference that a random woman they came across was in the latter category.
I can see two solutions here, neither of which is very good:
1) In order to promote gender equality, everyone at a conference should avoid judging people based on their gender. This would be ideal, but it's hard to fight casual statistical inference.
2) The conference could make sure that the people selling stuff at the booths and the people attending the conference have similar demographic profiles, so a random woman you encounter at the conference is as likely to be technical as a random man. In practice, though, this would mean preferential hiring of men for the promotional jobs.
Really, we need an option (3) of "get more women to be developers" but that's hardly news, and not something that can be solved in short order.
It's almost as though you need to get ugly women - if the women are too attractive, then they are written off as "booth babes". Which is kind of sexist in its own way.
It's one of the hidden sides of sexism in our society that annoy me. I try to catch myself whenever I find myself doing that, and have been pleasantly surprised.
A side effect of this is that those women that are attractive and intelligent tend to begin to hide it. So you get self-reinforcing behavior from society. Things like guys belittling smart women etc... The whole thing is annoying from the perspective of a guy that loves talking to non-white guys about programming or almost anything interesting. /squirrel banter mode off.
Case in point: Hedy Lamarr, who is probably more well known for her beauty than for her contributions to science (http://www.google.com/patents?vid=USPAT2292387)
Make them large and noticeable, on a lanyard probably.
How do you know if she was hired because she was attractive or because of other skills/attributes or a mixture of both?
I ask that at the grocery store when I have a question and I'm not sure if the person is an employee of the store or one of the store's suppliers.
Saying "Do you know anything about this product, or are you tits for hire?" doesn't seem like a great question either..
Though that might be a good strategy to discourage "booth babes", just keep asking shit they can't answer.
If you have "booth babes" (I think she did a great job in the article of defining what that term means), I'm not going to buy your product. I hate it and always have. Its trashy and demeaning, and I resent being grouped into the lowest common denominator when I go to view a product I actually care about. As demeaning as it is to women, I think a lot of men would agree that its demeaning to be treated like a dog who can be baited with a doggy treat.
If you have a good product, you don't need to lure in knuckle draggers who let themselves be led around by their reproductive instincts.