Maybe Tails hates fanfiction because it often goes against the original vision of the character. Fanfictions might portray him in ways that he doesn't like or in situations that are inconsistent with the official story.
Maybe in the fanfic, Kurenai has some actions that conflict with Naruto's beliefs. For example, she might oppose Naruto's way of handling certain village matters.
Maybe in some fanfictions, the writer wants to create a new plot where Naruto has some misunderstandings about Jiraiya. For example, if Jiraiya made a decision that Naruto thought was wrong regarding the village or his friends, it could lead to Naruto hating him in that fictional scenario.
Maybe he hates it because it often distorts the original story. Fanfictions might take his character or Naruto's in directions that he wouldn't approve of in the original Naruto universe.
One reason in fanfiction could be the pressure he faced. Draco was always under the pressure to uphold his family's reputation. He might have felt trapped in a role that he didn't fully embrace. And as he grew older, he saw the hollowness of it all. He may have compared himself to others who seemed to have more freedom to be true to themselves, and this led to self - loathing. For example, when he saw Harry and his friends being so carefree in their friendships and beliefs, while he was constantly constrained by his family's expectations.
Maybe Ash's character in the original work has a certain fixed image, and some fanfics about Serena deviate from this image he represents, so he hates it.
Well, it could be that the quality of some Natsu fanfictions is just not good. Poor writing, grammar mistakes, or uninteresting plots can make readers dislike them. Also, if there are too many clichéd storylines in Natsu fanfictions, like always having the same type of love interests or predictable adventures, that can put people off.
In some fanfictions, Jacob might hate Bella because of the love triangle situation. He could feel that Bella has led him on or toyed with his emotions. For example, if she constantly goes back and forth between him and Edward, it can make Jacob bitter and resentful towards her.
It could be that the cultural aspects of Christmas don't resonate with Naruto's character in the fanfiction. He comes from a different cultural background in the Naruto world, and the whole idea of Christmas - the gift - giving, the Santa Claus, etc. might seem strange and unappealing to him. So, the writer of the fanfiction might have decided to make him hate it for that reason.