Liberals and conservatives have different smell preferences.

A post faintly appropriate to this election day that is deciding the outcomes of very polarized contests of liberals and conservatives...Arthur Brooks points to an interesting article by McDermott et al. suggesting that our human mate preference - known to influenced more by political attitudes more than any other social, behavioral, or physical trait except religion - may be reflected in our smell preferences! Some clips from McDermott et al.:

Here we integrate extant studies of attraction, ideology, and olfaction and explore the possibility that assortation on political attitudes may result, in part, from greater attraction to the scent of those with shared ideology. We conduct a study in which individuals evaluated the body odor of unknown others, observing that individuals are more attracted to their ideological concomitants.

We conducted a study where participants rated the attractiveness of the body odor of unknown strong liberals and strong conservatives, hereafter referred to as “target” subjects; all “evaluator” subjects remained blind to the ideology of the target samples. One hundred forty-six participants between 18–40 years old were drawn from a large city in the northeast United States... Twenty-one target participants were selected for their high scores on opposite ends of the political spectrum (10 liberals and 11 conservatives) and provided body odor samples...Eleven of these target participants were female and 10 were male. Ideology was measured using the standard 7-point (strongly liberal to strongly conservative) American National Election Studies (ANES) self-report measure.

... individuals find the smell of those who are more ideologically similar to themselves more attractive than those endorsing opposing ideologies; recall that participants never saw the individuals whose smells they were evaluating, and the order of target subjects was randomized for each evaluator. Thus, the recognition of political alignment occurred through the medium of attraction, not recognition.

Some insight on the potency of odor might be gained from the participants’ comments and physical reactions during the study... a participant asked the experimenter if she could take one of the vials home with her because she thought it was “the best perfume I ever smelled”; the vial was from a male who shared an ideology similar to the evaluator. She was preceded by another respondent with an ideology opposite to the person who provided the exact same sample; this participant reported that that vial had “gone rancid” and suggested it needed to be replaced. In this way, different participants experienced the exact same stimulus in radically different ways only moments apart.