Really, I'd expect any community based on a personality test result to become insufferable. At least with fandoms, you have whatever dumb thing you all like to talk about; with personality tests, all you have is your stupid self, and you're all supposedly alike, so it just turns into a contest of who can become the biggest caricature.
This has me wondering if there's a subreddit for people of the various astrological signs and how annoying/entertaining that might be.