Please don't take this personaly or as a form of ofence, I'm seriously interested in the anwser but, besides the fact that as you said you tend to speak about personal stuff in casual conversations, why would someone need to know that you're asexual? I understand if someone asked you directly and you said "I'm asexual", but in the situation that someone asked you out why would you need to answer with something other than "no thanks"? (I understand that chances are the person will then ask why, but that's besides the point).
If someone comes on to me, I don't want to just say 'not interested' because I'm worried they'll think 'oh, she thinks I'm unattractive or something' and have their feelings hurt. So instead I explain about asexuality to make it clear that it's nothing personal to them, I'm never
interested in that sort of thing.
Also, I'm fascinated by psychology topics and love to describe psychological quirks to people, in the same way that fans of a show like to describe the show they're interested in.
For me sexual-drive means you have the hots for someone (tough it doesn't necesarily involve genitalia, the act of kissing someone is a sexual act), so I consider asexuality to not feel the need to kiss, hug or any other form of physical contact (which is not to say you avoid it, just that you don't seek it).
I like to hug and cuddle (but not kiss) my Mom, and will often sit on her lap or next to her. That doesn't mean I have an incestuous relationship with her.
Is there any degree of "this person is attractive looking" in it? Maybe not sexually, but if you saw your partner all gussied up and stuff, would you get warm and fuzzy feelings or would it be more of "oh, you look nice today"?
I can find people attractive. I don't really feel any strong reaction or act any differently, but I find looking at them pleasing. It's exactly the same as how I like the look of some artwork or whatever.
If I'm asking for advice on a story idea, don't tell me it can't be done.