Because I got the idea and it'd probably be stupid to make a separate book for it.
WARNING: This may burn some britches.

1. The fandom.
Reason: They seem to like overused tropes and Mary Sues.
2. Erin Hunter.
Reason: They've forgotten how to write good books and have continued the series even though the books seem to get crappier.
3. Tigerstar (Heart.)
Reason: He's a code breaker who has broken the code four times I believe, and has received no kind of punishment for it. And he's also a jerk.
4. Clear Sky
Reason: He abandoned his child, tried to kill his brother, and caused a war that killed many cats. And he got no punishment for it. Gray Wing got the punishment instead and he didn't deserve it.
5. Jayfeather
Reason: He's a jerk, and he exposed Mothwing in front of the clans and the medicine cats. (Even though she totally deserved it, it still doesn't change the fact that he betrayed his friend for no reason, except to give the Erins an excuse for drama that wasn't necessary.
6. Bramblestar
Reason: He doesn't listen to his son who's a medicine cat, he bickers with Squirrelflight all the time, and he lets the other leaders walk all over him.
7. ShadowClan
Reason: They get themselves into trouble all of the time, allow tons of rogues and codebreakers in the clan, allow murderers in the clan, allow themselves to be manipulated by everyone (Sol, Darktail, etc.), they don't follow the warrior code half the time, and most of the aren't even honorable. They need to get off their high horse.
8. ThunderClan
Reason: They're always butting into everyone's business and allowing kittypets into the clan. (They allow a useless cat like Daisy to be in the clan.)
9. The new warrior names.
Reason: They're freaking weird. (Twigbranch, Violetshine, Finleap, Bristlefrost, etc.)
10. Forbidden relationships.
Reason: They're overdone, they're annoying, and they're predictable.
11. The typos in the newer books.
Reason: They just show how rushed and lazily put together the newer books are.
12. The introduction of the supernatural.
Reason: Because it was unnecessary. The books started out as cats survive in the wild under the guidance of their ancestors. Then it turned into cats with superpowers fighting dead cats coming back to life.
13. Firestar's death.
Reason: It was rushed, slightly jarring, and kind of stupid.
14. The Clan's cruelty in newer books.
Reason: it's just plain uncalled for. They're willing to bring war upon a mother and her unborn kits! They are willing to kill her just because she's about to give birth and can't move! (I'm talking about the Sisters and Moonlight.) I mean, following the warrior code is great, but straight up cruelty is disgusting to read. I wanted to burn Squirrelflight's Hope after even reading it!
15. Mistystar's immortality
Reason: She should be dead by now. She's been around since the series beginning. She's was surpassed her age limit. It just goes to show how RiverClan isn't even acknowledged anymore and how lazy the Erins are.
16. RiverClan's neglect.
Reason: RiverClan is the least talked about out of all of the clans. Can we just push SkyClan and ShadowClan out of the spotlight for once and notice them? Maybe then Mistystar could finally die after being alive for generations!
17. Finleap's Mood Swing.
Reason: it was uncalled for and only happened to start drama between him and Twigbranch.
18. Bristlefrost's Complaining.
Reason: Because it makes her an annoying character if she can't get over Stemleaf rejecting her and all she does is complain.
19. Tree.
Reason: He's a freaking weird character that no one asked for.
20. Rootpaw.
Reason: He wont stop getting in trouble because he wants to see Bristlefrost. People don't want anymore different clan relationships! This is why people are getting mad at you Erins!
21. Squirrelflight's Hope.
Reason: Stay away from this book. It's a dumpster fire that didn't need to exist. It is easily the worst book in the series and didn't need to exist because the Erins should have just explained the Sisters in the story instead of making you go out and waste your money on this dumpster fire book.
22. SkyClan's Names.
Reason: They're really weird. Weirder than the rest of the clan names. Example: Billystorm, Bellaleaf, Rileyleaf, etc.
23. Mapleshade Should Have Went to StarClan.
Reason: She didn't deserve the Dark Forest. Just because she murdered out of grief doesn't mean that she deserved to rot in the Dark Forest. She should be in StarClan where she can see her kits.
24. The Codebreaking.
Reason: The code is there, yet everyone breaks it. If there's a code, it's there for a reason. You should follow it.

What Happened to the Dark Forest?
Like seriously, this isn't much of a thing I hate, I'm just curious what happened to it after the battle. I don't remember. All I remember was that Spottedleaf died a second time.