Trade shows can be one of the greatest uses of an organization's resources. Or it can be one of the biggest wastes. It all depends on having an actual trade show strategy.
At most trade shows, people are leery to give out their contact info because of how they're going to get contacted. Or, on the flip side, the enticement with giveaways has gone up and up, and they'll give it out to anyone with a good enough prize, whether they're an actual prospect or not.
Let's assume for a moment you're giving a huge prize away like a big screen television. Someone approaches your booth, sees what you're giving away, and starts filling out an entry form.
You walk up to them and say, "Can I ask you a crazy question?"
They respond, "Sure."
You continue, "Do you have any interest in any way, shape, or form of actually talking to us? You can enter either way, but we hate to bug people after the trade show that don't want to be bugged."
Right then, you've done something completely different than the other attendees. You've opened the door to potentially have a conversation. Or, you'll close the door and avoid wasting your time.
Of course, you also have to have a strategy for after the trade show. Typically two things happen.
First, companies put all the info on a shelf. It either never gets used, or it gets used months or years later when the sales pipeline has dried up. "Hey, remember that trade show we were at six months ago? Let's pull out that list!" Then the people don't even remember you.
Second, companies are so eager that it puts all those people on an email blast. The email may even go out before the person has walked away from the booth! And all the email has is info like, "Here's why you should do business with us!"
So what do you do? If everyone else is giving away something, don't. If everyone else is bombarding people with communication, don't.
The key is to do something that's different from what everyone else is doing. You need to do that before the trade show, at the trade show, and after the trade show.