Okay, so I’ve watched a few ecchi anime time to time ;P, you can call me a hentai or ecchi but I consider myself an otaku lol…there has been a  couple a good ecchi anime that I enjoyed watching like ikkitousen, Queens blade, and one of my all time favorite GOLDEN BOY!!!! There are others that are just as good like highschool of the dead that I cannot wait for another season! 
Back to the topic Highschool DxD, I don’t know what DxD stands for my only assumption is the main characters bust size, lmao. So the story from what I get is that the main Male lead is your typical hentai/pervert...

I love it when a character is shown having sex.
Even if it’s only a fanwork.
Even if it’s completely unrealistic.
Even if the character would never do it, ever.
I have written smut fanfiction.
I have created characters just so they can have sex.
I love gratitous panty shots, even if it’s just a cheap thrill.
I love to see clothes rip, the more skin, the better.
For that matter, impractical, sexy outfits just make me smile.
Zettai Ryouiki holds absolute territory in my heart.
I love to take scenes out of context to make a character seem more perverted than they are.
I love shows that have their base...