Just in case tossing cheesy pickup lines at people in venues which are inappropriate for finding dates wasn't awkward enough, you should film them while you do it. They'll appreciate it all the more.
They could be each others' girlfriends, they could be asexual, they could be completely unattached, but yeah, they know that the unfortunate reality is that many guys just won't give up unless they know the woman is already claimed by another man.
I was at a medical conference at a place similar to this and watched in horror as an Asian friend of mine burned out just as hard with this plain looking Asian girl who was working a booth. I don't think people realize how unpleasant and boring those things are and that the last thing girls want is for awkward people to hit on them.