• generic DNI (racist, homophobic, etc)
• you are, associate with, or defend pedophilia
• you're just looking to start shit like drama or a fight
• you're an excessively negative person on the regular
• you tend to deliberately bash people's interests, favorites, comforts etc. for whatever reason (i've dealt with that too many times before and it's never pleasant)

I don't think I'm generally that hard to get along with, so long as you're at the very least a decent person.

(I should also note that if I notice you exhibiting problematic behavior (especially something from the above list) and you make no effort to change that, there is a very real chance I will softblock you simply because, again, I've dealt with similar cases far too many times and I just don't like putting up with that sort of thing)