so as I understand it from reading through but maybe I have made a mistake, they didn't actually unslop anything, they made slop and the best slop won?

If it was to unslop I would expect:

1. Prompts done as in original

2. Stories chosen best of slopped. Then the person who wrote prompt gets to choose someone, not themselves, to take story and "unslop" it.

3. Prizes for prompt. Best unslopped version. Metrics for best unslopped version is of course how good it was, but also how much work was done to unslop it, if you basically rewrote everything and it was as if you took the prompt and wrote your own story that would decrease value of unslopping.

obviously above just suggestions for how I think an unslopping contest would actually work.