What if they aren't American though? Are right-wing people from Europe or Latin American supposedly more physically attractive than left-wing people from there?
They are talking about pols, not voters. They didn't do like a HotOrNot test. Although I imagine that racism plays a factor in any determination like that. Maybe amongst conservative minorities and liberal whites, they are more objective.
There is no way to be "objective" about physical attraction.
There are many universally agreed upon signs of physical attractiveness. Just because one is not attracted to someone does not mean they cannot acknowledge that that someone is attractive.