I don't feel sexy when sick. In fact, most people I know don't feel sexy when sick. I was ill the day I met my ex-husband and he still wanted to try it - so he tried going down on me while I was in an office chair. It flipped and I got a concussion.
Despite that, I still married him, and the marriage turned out celibate.
So, the one time anything sexy was attempted while feeling sick, I ended up in a marriage from hell. I don't think I'll start wanting sex while sick anytime soon.