There aren't any really "bad" Katy stans. They're all generally really sweet and fun to talk to. They aren't quick to throw shade towards other artists and I've never had a problem with any of them. They usually don't take any shade too seriously nor do they act delusional.
Standouts: Teen Dreamer, HotNCold
I don't know of many Katy stans, so I apologize if I forgot you.
Make sure when you get to J. Lo, call he stanbase the Penny's.
I used to be a J. Lo stan. That was until Brave. I couldn't stan for that bitch after Brave. I still love her personality and Love? is fantastic, though.