Well, the best story porn often has a compelling narrative that keeps you engaged. It also might have well-developed characters that you can relate to or find interesting. And, of course, the level of sexual content might be just right for some people's tastes.
One story I heard was about a woman who found out her partner was cheating. Instead of making a scene immediately, she quietly collected evidence of his affairs. She then sent an anonymous package to his workplace with all the proof, which led to him getting fired and his reputation in tatters.
In a language exam, a girl was copying from the person in front of her. She was so focused on copying that she didn't notice the teacher coming up from behind. The teacher saw her looking at the other student's paper and caught her. It was really embarrassing for her.
There was a time in a card game. A player had a small mirror on his watch. He used it to peek at the cards of the opponent. He thought he was being sly, but eventually got caught when someone noticed the strange glint from his watch. It was quite a funny cheating story.
There was a case where a car's body was altered in a sneaky manner. The team made the car more aerodynamic in ways that violated the NASCAR regulations. They thought they could get away with it, but were eventually caught. NASCAR is very strict about the body shape and any modifications that could give an unfair edge in terms of speed and handling.