I would guess that most of us on Zity (if not all of us} are "obsessed" in varying degrees with our assholes, and with the possibilities for erotic play that this part of the body offers. But this "obsession" is not a bad thing.
As a child I found out quite early that "it felt good down there". My adult supervisors were quick to suppress those urges in me, arguing that the asshole was a dirty place. And so, I had my ass fun only behind their backs. Luckily I was seldom cought, but I did feel guilty and "different". It just felt too good to abandon. So I became "obsessed".
As I grew up I found out about the huge amount of nerve endings that surround the area, and it become clear why the asshole was so sensitive. But I still felt guilty and "different". Only after reading the Penthouse Forum back in the nineteen-seventies, and much later after finding the site Enemas for Fun on the internet did I completely realize that I was far, very, very, very far from being alone regarding my anal preferences. I stopped feeling guilty and I stopped feling different. And definitely I felt less "obsessed".
Although I think society's attitudes towards uncleanliness are well grounded, the problem is that these attitudes can also become "obsessive". Fortunately, albeit very slowly, social mores are becoming more open, realistic and more understanding.