Re: Out the b*****ds
"Go right up to that sales booth and tell them.
"I would have been interested in your product but one of your sales men was a total ass, so I won't be buying from you ever again"
Word WILL get around the company in question, even if its not in official channels, the talk over the water cooler will cause embarrassment."
Stories like this make me ashamed of my gender at times, and it's not just IT world, I've heard similar (and worse) tales from female friends who're seriously into the sci-fi / cosplay world, with the minority (I hope) seriously letting the side down.
Reporting the bad behaviour to the relevant companies, especially when they're on hand at the conference, sounds like the best option. Far better than simply ignoring their stand, which does nothing to make the company aware of what their staff are doing or give them a chance to resolve the issue.