I went to an event recently and someone went around handing out small flyers for an upcoming nearby first-year convention. A while later, I was looking at it when a guy came up to me and told me that the guy running it was running a charity scam. He didn't give his name, but introduced himself as the organizer of another convention in the same town as that first-year con. He told me that the organizer of that con went to his con's Facebook page and sent invites to everyone on there. Then he walked off. I could barely get two words in. He clearly wasn't interested in discussion and only making sure everyone thought that new convention was some kind of scam.
I'm sure neither the person giving me the flyer nor this competing convention's organizer knew who I was, so it's safe to assume this was happening to other people at the event as well. It's completely distasteful behavior.
I've actually heard that this guy has made the "scam" allegation against the new con previously...but that sort of behavior of making baseless accusation's not going to win him any friends no matter if it's true or not. It's a lot like some of the mudslinging we see in political campaigns. Nobody will come out smelling like a rose. I've never been to the accuser's convention and his behavior ensured that it will likely be a long time before I set foot in his event.
If this guy had any smarts, he'd welcome that new con to his town with open arms. They're not the same weekend as him. In fact, they're FIVE MONTHS earlier! That's more than enough time between the two events. He should be working with them and asking to do some cross-promotion. Advertise in their program, they can advertise in his. Offer to give them a promo table at his event if he can have one at theirs. If they work together, either convention's promotional efforts will also help the other convention in the end.
Nobody has ever managed to shut any con down through badmouthing them. There are plenty of disreputable and sleazy people out there still running conventions year after year. Cons have only ever failed through the efforts (or lack thereof) of that con's own organizers. If this guy has some actual proof that the new con is indeed a charity scam, he should talk to law enforcement or report it to the Federal Trade Commission to have them look into it. Walking around some other convention and saying nasty things is making neither him nor that other con look great.