So I'm going through the beta process right now with a short story. After my second round of betas, everyone seemed to love it. They all said it was really fun to read, but a few of my readers had some very minor understandable grievances. I fixed the grievances, and submitted the material for a third round of beta reading.

And now it's universally panned.

I think the lesson learned is, if everyone seems to like it, don't touch it. At all.