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.
YMMV: Inu X Boku SS
Awesome Music: The first opening, "Nirvana," by MUCC, if for no other reason than those mind-blowing vocals.
Fridge Brilliance: In Chapter 12, Zange off-handedly remarks to Watanuki that the path he takes will be decided in 2 days. Then in Chapter 15, believably about 2 days later, Karuta gets attacked and seriously injured, starting a series of events that decidedly impact everyone's paths and the plot itself.
Fridge Horror: When you consider that Zange's power lets him see into the future and into his past incarnations, his life is pretty much a single long, endless loop of meeting friends who don't remember him only to watch them die in the same way over and over again.
Ho Yay: Between Karuta and Ririchiyo such as former trying to feed latter, much to Nobara's delight.
Almost entirely one-sided, but also Zange and Soushi, as Zange tends to flirt and fawn over Soushi when they're together. Soushi lets him without protest though.
In the reincarnation timeline there seems to be shades of this occurring between Zange and Renshou, with them playing at a "mommy" and "daddy" act.
Uncanny Valley: Maid 3, his eyes look like they were painted on his face.
Unfortunate Implications: Ririchiyo has never had real friends before moving to Ayakashi Kan. In other words, people like her can only be happy with other hybrid humans.
To be fair, arguable exceptions do exist, such as Kotarou who is the ordinary child of an Atavist (who also married an ordinary human), and he gets along quite well with the rest of the gang. There's also Kagerou's mother who clearly cares for the well being of her son and his friends; she is the woman who rescued Soushi twice from his borderline abusive family, and cared for him henceforth until he came of age.