Lets see now
The ultra innocent girl: why would a married 30 something woman act like she's never seen a dick before? "Oh my... is this ____-san penis?" like she was expecting something else in his pants? A jack in the box maybe?
When the main male character is a sociopath, now i'm all for kinky corruption stuff but when the male character is the sexual version of Light Yagami I just can't get into it. There is no enjoyment of the fact his hot classmate is sucking his dick, just an evil fucking smirk and a voice over about him gloating.
and my number one pisses me off is the "bad end" I know no one watches hentai for the story but I've seen a few, Milk Money, Foxy Nudes, and Mistreated Bride, which i'm still mad never showed her in the wedding dress like on the covers, and then BOOM, I go from watching a guy-on-milf with big tits and lactation to she killed her daughter, starved him to death by not letting him have anything but her breast milk, and buried them in the yard next to the LAST guy she did this to? My erection just commited seppiku. At least dojinshi you can open the pages and see the content if its not plastic-wraped. But hentai anime you're taking a shot in the dark if the DVD with the hot sexy girl posing happily on the cover will be nothing but watersports and rape.