Let the stories continue...
My very first DM (from all the way back in 1983-1984) was a really bad DM. Really bad. I often say that if I do the opposite of what he would do, then I'm probably DMing the right way. Here is a short list of some of the things he did during the time I played with him:
* The biggest gripe I had with him was that we would spend an hour rolling up characters (1st Edition AD&D), get an adventure started, and then we would have to quit because he didn't prepare much. Then, he would always say: "We'll continue this next time." And we never did. Every time we played (which could be several times a week), we rolled new characters because he had a new idea. Whether it was 1st level characters or level 17 characters, he promised that the next game was definitely going to be longer than a single session. Nope. Never happened. I still have a box that has a stack of characters I created in those days and were only played one time. I used them later as either NPCs or as quick characters when I got to play in another game.
* During one game, we generated 1st level characters. I played a paladin. The game started as we spotted a goblin coming down the road dragging a large sword behind him. We stopped to question the goblin, who immediately went hostile. Given no choice but to defend ourselves, we ended up killing the goblin. I picked up the sword. It turned out to be an artifact...Excalibur, to be exact, which was a +5 Vorpal Holy Avenger. Yeah...a goblin was in possession of that. Of course, I never got to use it, since the game was never continued (see above).
* This DM enjoyed being a "killer DM." He wanted to see how fast he could kill us. Given that we didn't continue any games beyond a single session, this didn't bother us much (no attachment to the characters). We longed for more, but just went with it when we were desperate for a game. One day, he took a crossword puzzle out of the newspaper and put it on graph paper in a 15x15 block. Our characters had to make it from one corner of the room to the other. The white spaces of the crossword puzzle were safe spots, and the black spots were instant death. We had no way to indicate which was with, since we couldn't see the crossword puzzle he had used and he gave us no clues. We lasted about four steps.
After about a year under this guy, I took over DMing duties when he got busy. That started a career of being a DM for me (and me loving it). Not only was I a better DM, I could run a campaign that would last for years and not attempt to kill characters or require them to be started over each session. So, much thanks to that guy for showing me how not to act.
I should say, though, that even though I didn't like how he handled himself as a DM, he and I were friends for years (lost contact with him in about 2001). So, he wasn't a jerk in real life (mostly).