Let me just say this, by way of opening: I am a colossal hypocrite. I've been posting all these stories of my friends' and others' horrifying DMing, and neglecting the elephant skeleton in the walk-in closet, so to mix metaphors.
I once co-GMed, and then solo GMed, a Deadlands game, both Weird and Wasted West. In fairness to me, the fellow with whom I was GMing came up with a lot of the more offensive parts and stupid decisions. In fairness to him, I came up with much dumber decisions than he ever did. Now one of the players has posted his campaign journal...and reading it quite predictably makes me facepalm constantly at how asinine we were being.
Anyway, nine perpetually stressed-out engineers play a campaign devised by a biologist and a mathematician during a 48-hour post-exams celebratory Red Bull haze, where we started with "Hey, what if Teddy Roosevelt was born a decade sooner so he could be a Texas Ranger pulling the party together as a massive Indy Ploy?" and kind of went all kinds of crazy from there. What could possibly go wrong?
The answer is a lot. But then again, I had "help", and it was the first long, storied campaign I ever ran. And lots more excuses. Bah. A lot went wrong, but honestly the behind-the-scenes stuff, should I ever get around to writing about it, was hilarious in hindsight.