I don't think there are straightforward rules when it comes to story quality. You can have good fetish writing and bad writing, just as in the case of any other literary work.
It's easier for me to tell you what I think doesn't work. If a story starts with a ticklee waking up in a dungeon, naked and in bondage, I usually just stop reading right there. Similarily, if half of the story is made up of HA HAs and HEE HEEs, I will not be reading it. Another pet peeve is the author's inability to insert dialogue in the text. I'm referring to something like this:
"He approached her, a feather in hand and a sly grin on his face.
MARTHA: What are you going to do to me?
THE MAN: Glad you ask. I'm going to tickle you. I'm going to tickle you until you tell me everything I want to know."
This is writing 101. Unless I'm reading the world's first tickle fetish theatre play, this just shows that the author has no idea what he/she is doing.
Other than that, I think it's just a matter of practice and learning through trial and error. Take your favourite tickle stories and dissect them, see what makes them work. Then, write your own. If it's not good write another one and another. If you write a lot of stories, there is a chance that at least some will end up being good.
I'll end here and leave you with the link to what I consider to be the best written tickle story I ever read. Here's "
The Laughing Madness".
