I'm making a list of hentai mangas, not anime by category:

-Visuals: The quality of the images.

-Plot: The story must be creative, minimal amount of cliche, and of course that it's not only about sex. And NO PARODIES.

-Sex: Must not always be random. Most have a purpose in the plot and/or to not bore the audience.

-Characters: Like the story, must be creative, and have a minimal of cliche (except tsundere). And for the love of GOD, NO sexy teacher ******* her student!

-Genre: From the first chapter you must know the genre. For example: Romantic Comedy(Ore Tama), Horror/Gore(Bible Black), etc.

-Popularity: The series had a great market, and sold a high amount of copies.

Btw, no Adultery.