These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
It's pretty clear that Genma is one by the end of the series.
Havoc, before we meet her.
Daisuke does an impressive number of horrible things in the short time we see him. He sleeps with his charges (including his cousin), posts web-porn of his conquests, tries to deny it when confronted about it and when that fails, tries to blame his lovers for his wandering eye and refuses to apologize for anything he did. He apparently gets a teacher to agree to sleep with him by drugging her, hires a gang to "take care" of one of his mouthier lovers, and tasers his would-be and eventual killer after she decides to spare him.
Claude really has no redeeming qualities to speak of. He ends up slaughtering an entire building full of contractors who wished to live peacefully. All while wearing that evil bastard smile, no doubt.
Of course, Suou also has her fans, who thought that she gave the season a fresh approach which it sorely needed, since season 1 all over again (just substituting Amber with Yin/Izanami would have stagnated the plot.
Les Yay: Buckets aimed at Misaki. She doesn't reciprocate much, though. In all fairness, pretty much every character has at least a little attraction for her, not just the women.
Magnificent Bastard: Amber. No surprise considering her powers to travel through time gives her the upper hand to manipulate people and events.
Daisuke posting web porn of his conquests whilst they remain ignorant of it. With badly blocked out faces. Then hiring a gang to rape Azusa AND Kyouko, with Kyouko as an unwitting accomplice, just so he can "rescue Azusa" or so she can't tell on him.
The callous and horrible way in which Tanya kills her other best friend/crush Nika.
Claude's massacre of a group of Contractors who just wanted to live in peace. Particularly since given his powers, he had no real reason to do it.
Complete Monster: Ilya Sokolov, a creepy motherfucker even by Contractor standards. Just in case he wasn't horrifying enough, he casually revealed that he had been a Serial Killerbefore he became a Contractor. The guy who hired him thanks Hei for killing the psycho.
Genma, arguably, crossed into this territory.
Crack Pairing: Hei/Hazuki. Hilariously enough, the only shipping pair to actually get any action. That remuneration sure is awkward, huh?
Crazy Awesome: Playing chicken with an airplane. Hei. Genma. Episode 9.
Kiko's very existence serves as a comedy relief element for the series. Other than Mao's nervous sweat-beads, she's the only other character who's frequently prone to over-exaggerated anime emotions, such as Wingding Eyes whenever an opportunity to make money comes around, and Expressive Hair.
One great Kiko moment was when she and a friend were complaining about Adaptation Decay of some unnamed series.
And, after Mao wakes up in Amber's headquarters, he gives a long, dramatic monologue about how contractors always do the logical thing. When he get caught by the others for trying to non-chalantly walk out of the room, he tries to logically respond with a "Meow."
Then there's the time when Hei was infiltrating a restaurant and a violent, drunk customer decided he had a problem with the waiter. Result: Huge tough guy trying to beat up a cute, skinny little waiter who isn't doing that great of a job of hiding his epic ninja skills.
The time when a couple of door-to-door missionaries went after Hei. "Um... I just want to put away my groceries..."
Most of the OVA. It's basically an omake parodying the main series, particularly mocking Hei's Chick Magnet status and the fact that a White Mask of Doom and a change of clothes really shouldn't be that effective of a disguise. Highlights include slightly loopy fangirl Mayu crushing on him due to his "sexy collarbone" and writing him into her yaoi fanfic (which Yin reads), and what is possibly the absolute silliest Reset Button in the history of fiction.
Leave The Plot Threads Hanging: The complete lack of explanation for the Gates, Alien Sky, and the like generally works well enough that resolving exactly what's going on would probably be a bit of a letdown.
Hei will die. But his soul will choose to go back in time, the time when he was happiest, and he will be at season 1 first episode. Suou who loves Hei wants to be with him too and wants to be in a time when Hei'd love her, but since he already loves Yin she'll go back in time before Hei is born, and became his mother.
Moral Event Horizon: If you somehow still harbored any sympathy for Genma, the throwaway comment in the last episode that he was the one who killed Youko and the implications of having raped her prior or even worse; after her death pushes him straight into Complete Monster territory.
Narm Charm: The Gratuitous English lines at the beginning of the first opening should by all rights sound stupid. Instead, they're awesome, in an over-the-top, Memetic Mutation kind of way.
Selective Squick: In general, the more squicky you find lolicon, the less you'll like the second season. If you can ignore the subtext completely and don't mind Hei's jerkification, it's actually quite good, but for others... yeah.
Sequelitis / Seasonal Rot: A solid few of the fanbase are very and vocally dissatisfied with the new tone.
In season 2, Genma invokes the trope in hopes that it can apply to him ("Hey, having an unfortunate past can score me some Moe points!"). *
That'd probably work better if Hei didn't have the Dark and Troubled Past thing cornered and Amber, Suo, and Yin weren't covering the moe.
Woolseyism: The first two episodes make more sense and fit the tone of the rest of the series quite a bit better in the dub; in particular, they changed Jean's completely-inconsistent-with-everything-else comments about "installing a personality" to something like "Contractors have feelings too" and replaced Mao's inexplicable line about Hei's coat only being bulletproof when he wears it with an excellent Deadpan Snarker moment along the lines of "Hei doesn't just wear that coat as a fashion statement."
