There are 2 main ways (and many combinations of them) to rate storygames (and movies, books, etc.):
1. Be subjective, rate a story based on how you like it.
2. Try to be objective (like a literature critic), base ratings on things like originality, characters depth, writing quality, etc.
I have a hard time rating stories because 1) and 2) often conflicts.
Often a story objectively has a decent/high/very high quality and it's theme/genre is interesting, but it is boring or irritating for me. So rating it either high or low feels wrong or unfair and I don't rate it.
There are some short badly written stories that are still fun to play. I feel ok to give them slightly higher rating, it's not as bad as to downrate a good story. But it still feels somewhat wrong.
I have a bunch of played stories waiting to be rated until I figure out how to do it properly (I won't name them).
So how do you rate a story? Especially if you don't like it, but see that a lot of effort is put into it and others like it.