1. More or less any and every dere character. Fuck them all, especially Yanderes and Tsunderes.
2. When an anime, harem or not, includes much more fanservice than it needs to have.
3. When every character has a horribly edgy past (I'm looking at you, AoT and God Eater)
4. hand-in-hand with #2, panty shots.
5. When the logical choice is passed over in favor of the dumbass choice for the sake of plot.
6. Deus-ex-machina.
7. When the titular character of the anime in question has little to nothing to do with the anime (I'm ESPECIALLY looking at the piece of shit movie titled Date A Live: Mayuri Judgement)
8. When they have some cringey "bring forth the end of humanity for the advancement of humanity" kind of character.
9. When damage from a fight gets repaired in > 1 day. Extreme cases go to a few hours on this one.
10. When the anime takes a tangent off the source content that breaks continuity.
11-. Much, much more that isn't popping up from the top of my head.