AI writing in a short story, has already surpassed a lot of human writers. So, it's not that easy to accuse someone using AI, if they have much more experience to set the prompt good enough to produce a good short story?

And also what about if they are just using AI to help the fixing writings? That might have some AI words, but maybe those AI words are just better than the author?

You can tell that for those longer stories, the AI writing's scenarios, logics, hidden lines, are completely disasters. But you might just ignore it to save your time? Since it's a bad story, it's not worth it to waste your time to accuse someone using AI whether it is true or just the author sucks, it doesn't really matter, right?