Well Sailor Moon Wannabe-Hentai has been proved already to not actually be a Hentai. Since this is settled, I'd like to add the appearance aspect of bad Hentai. For example, the first Hentai I saw was NightShiftNurses ep4, an extremely well-drawn one, and the second was Cool Devices. At first I was, just like the most of us, disappointed/displeased by the terrifying quality-leak. However, if you think a badly drawn Hentai is automatically bad, think again:
Among with LaBlueGirl, Cool Devices was around the first proper Hentai ever, paving the Way for it's successor: average and quality Hentai which we love.
And so, on topic, the *worst* Hentai imo is *Dyogrammaton* since it lures people with a very delecting cover but the Movies themselves certainly are of obnoxiously poor quality, which is not particularly unique (See Fairy of the Forest or Harumi's bad play for Example) but it is some kind of recent.
I chose to award *Dyogrammaton* the "worst Hentai" title because it is certainly more poor compared to other 2007 releases than pretty much all other bad Hentai movies compared to releases of their time.
I do, however, also hate "Bondage Game" for the irrevocable Images forever burnt in my Head. Rather than the grotesque conent, I tend to blame the innocent-looking but highly deceptive title and the lack of warning, though.