Came to this article because I heard about DashCon, which apparently was going to be a TumblrCon and essentially failed horribly, awfully, all over the place. Various link-caches took me to this summation of what would be known as "TentMoot." It seems like a fascinating story that unfortunately isn't fully told on this page.
Further reading can be found here.
I am sharing this for my fellow LOTR fans, Meriadoc of course immediately jumps to mind.
Oh man. I haven't gotten to reading this yet, but you mentioned DashCon.
It wasn't just a disaster, it was a massive scam perpetrated by 14 year olds. Kids organized the whole thing, and after it was already happening for a full day in the hotel, they said they were being asked for money from the hotel or they'd be shut down. That would never happen, and then people willingly donated over $17,000. They also refused to pay the Welcome to Nightvale performers who then bailed.
A bunch of kids made off with 17k.