If you ship incest or are into incest play then I dont want anything to do with you:) same with romanticizing r**e, pedophilia, beastiality, self harm or being transgender.
Fun fact!! Being transgender isnt a part of your personality, it's just a simple fact like "we all die eventually" or whatever, dont make a big deal about it.
Self harm in fanfics is especially annoying to me, in very very few cases (at most two) the fic mentions it without being insensitive, but alot of times it's just unnecessary and, frankly, disgusts me.
The others I listed just.. They should be obvious.. This isn't up for debate.