If it's something complex like "yandere" just leave it be, but don't do that for most sexual stuff. Putting a phrase in another language doesn't make it less vulgar. At most all it does is add a thin layer of distance between ideas. If somebody asked what the hell "paizuri" meant you'd probably say "it's Japanese for 'tit-fucking.'" If you want to be professional be dry and clinical and call it mammary intercourse or something. We're all perverts here, don't try and sugar-coat it.
I don't feel like checking back, so I'm just going to put down my ideas. (You said you wanted class...)
-forcible rape
-anthropomorphic beings
-sadomasochism and bondage (SMBD)
-identical twins
-hyperphallus (Giant penis, in greek)
-hyperonnus (I think it's giant breasts, but I'm not sure)
-pedophilia
-zoophilia
-necrophilia (Is this even on the site?... let's hope not...)
-vaginal intercourse
-anal intercourse (Adding intercourse makes it smarticle.)
-fellatio
-tsundere and/or yandere
-group intercourse
-nekonimi (Cat ears)
I'm not into to most of this, though...
"Super" for those hardcore mangas
"light" for those with very little sex or extreme behavior
"Slave" for when one or more characters is subservient to another sexually or otherwise - mostly sexual
and you can either use abrevations to describe what holes are being used
i.e AL anal, OL oral, VL vaginal
then what would seem to be the normal tags
incest
loli
Shota
Tentacle
Swimsuits - also bloomers
Maids
Futanari
if it`s sex with family members then it`s ok :D
btw what are the other genres ?! i don`t know what they mean :D i just dl and enjoy :D but incest is more hot :D
like family play !!! ^.^
I would dearly love it to be a simple, clean-cut system, but the fact is that there are a lot of fetishes which are common in material - sometimes only a page/scene or two - but don't get around much: bondage, urolagnia, DP, monster girls (for example). The result is people like me craving the stuff, and leaving it untagged or under a generic 'fetish' tag would suck for everyone. Some kind of sub-categorisation could work, or some other means of indicating minority content, but I'm not sure how you'd do it.
-Harem
-Incest
-Rape
-Reverse Rape
-Mahou Shoujo
-Bishojo
-Bishonen
-Futanari
-Housewives
-Romance
-Juujin (covers nekomimi, inumimi, and etc)
-Uniforms (covers Office lady, swimsuits, teachers, maids, waitresses, nuns, etc.)
-Traps
-Virgins
-Underworld (covers Yakuza, Mafia, etc)
-Eastern Fantasy (ie Sengoku period, or Ming Dynasty, etc)
-Western Fantasy (European Medieval)
-Sci-Fi
-Yuri
-Yaoi (so I can avoid it, if any is posted)
-Guro (so I can avoid it, if any is posted)
-Non Hentai
Out of all of them, the normal, but lacking offensive word ones will do, but I have to make a request, even with the small number of these, I really would want you to put up the category "Gender Bender". That is my only request.
Maybe the tags should be more general and not specific? I mean If we try to classify a doujin with the tag, "Tittyfuck".... It's specific, too specific.... It should be the general genre right? Instead of "Tittyfuck" go for MILF..... (since you can't, in all sense, tittyfuck a loli....)