Total overkill of the following:
1. Overpowered Villains
2. Spiky Hair *cough DBZ cough*
3. Weak support characters (one character is almost overpowered, while the others are sub-par with their powers)
4. Emo characters (like what Destinyheroknight said)
But really it's up to what each person like, you know? I don't like any of the HST because my tastes are different. I'll say that the Black Butler manga is better than One Piece because Black Butler is more to my tastes than One Piece.
I hate the idea among some internet fans that anything outside of the HST is better then the HST(No,hellsing is not better then One Piece and Naruto ,killing Nazi Vampires is a shitty plot.No,DBZ is not better then Naruto and One Piece cause it is more popular guess what Justin Bieber is popular too.)
Characters with excessive Transformations and forms. 1 or 2 are OK but 3 4 5 !!! come on now
The female characters who are there just for eye-candy, does get tedious after a while.
The cocky A-hole rival to the main protagonist, it get old to me after seeing it so many times.