One story I stopped reading early on - the MC gets attacked and almost murdered by a local bully and his clique. A few days later he's inviting him to his dungeon party because he needs a tank and it would be inconvenient to have to look around for someone who didn't just try to murder him. Because when you need someone to trust with your life, it's a murderous bully you want.
One I stopped reading like two hundred chapters in - the MC's friend gets murdered and in response she kills about a million people (99.9999% of whom had nothing to do with it). And then the story just keeps going like she's not now a tiny Hitler.