One simple tactic they could use was having attendees wear the badges at all times like SDCC does. I also saw several people walking around with no badge. Many I'm sure had it in their pocket or bag, but I know a few used that "sneak in" system Comic Girl writes about. Make them wear it, if security or NYCC staff see someone without one, ask to see it and tell them to put it on. If they ain't got one, give them the boot.
I guess the reality of all this is that NYCC is now reaching the level that they have to care and begin to put these measures in place because they are getting so big. When you were smaller, it wasn't such a big deal, but it will be now. It's like the posts we had about attendees taking advantage of disability services at SDCC. Only at SDCC is it so big and so competitive that this is a true issue. I bet at smaller cons this is just not a significant issue, it's not at NYCC either, but when get that big and popular then all that s**t starts to come out. Sad.