"Do you work here?"

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.

If she's working the booth then she is working there in one way or another.

Saying "Do you know anything about this product, or are you tits for hire?" doesn't seem like a great question either..

I misread and thought jiggy2011 was talking about not being sure if she worked there. I would assume someone hired to work a booth would know something about the product, and know who to point me to if they don't have an answer to my questions.

Talk to her. After the first sentence you will know the difference.

Depends if you start with a technical question.

Though that might be a good strategy to discourage "booth babes", just keep asking shit they can't answer.

That's not really good for the booth babes or the technical women. The booth babes all get thrown out of their depth repeatedly, while the technical women have to deal with every single conversation starting out by getting quizzed live to make sure they belong in the club, which sounds totally stressful.