I can offer two points of view on the matter:
When I was in college I dated a teacher at my same university. I was an bit older than the other students, and a junior. He was teaching freshman, and also taught a class I'd never take. We were pretty equal when it comes to maturity levels, and thought now I don't know what I saw in him, at the time it was your normal, healthy, albeit short-lived romance.
I feel that as FT's we have an obligation, not just to our students and our own reputations, but to the reputations of other FT's as well. We have to think, "How will this affect these Chinese people's views of Americans, Canadians, Brits, Aussies, etc?" I think that dating a student leaves a bad impression in school's minds (this means foreigners, and not other Chinese teachers), and that's just not fair to the teacher that will come after you.
And, I just have to admit there's something distasteful to me about the whole idea. I love my students, but they're really little kids in a lot of ways. Younger women are already at a disadvantage when dating older men, but this maturity divide could be insurmountable! Also, the fact of the matter is that if you're willing to abuse the teacher/student relationship, I can't imagine you're too great of a person anyway, and that just leads to a more twisted relationship.
As for dating college kids who aren't your students, someone said that as a teacher ALL students are your students. And I'm inclined to agree with them.