Uh, well, I misunderstood the topic at first, and what I thought it was was people who I find utterly disgusting who I'm supposed to accpet as sexy in a movie but don't. And immediately Michael Douglas came to mind, in any role, really, including the role of Catherine Zeta Jones' husband.
But, as for what you were really asking about, I'd say Josh Hartnett in Virgin Suicides. Usually he's not my type at aaaaallllll and I find him to look kinda dopey, but as Trip Fontane, very hot.