See "A disgust theory" in the chapter on ambivalence for a statement of the theory. In this appendix, I discuss it in more detail.
The simplest prediction of the disgust theory, that disgustingness and appeal of a sexual stimulus should be negatively related across individuals, has at least some support. The first paragraph of section 2.1 of Fessler and Navarrete (2003) reels off some relevant citations. Vulink, Denys, Bus, and Westenberg (2006) found that women with OCD were more disgusted by sex and had less sexual desire, less sexual arousal, and less satisfying orgasms. de Jong, van Overveld, Schultz, Peters, and Buwalda (2009) found that vaginismus predicts disgust, at least about sex-related stimuli.
Where the disgust theory departs most clearly from TMT is that it predicts less ambivalence in the sense of simultaneous attraction and repulsion to the same thing. Indeed, the disgust theory is founded on the idea that we're most disgusted by the sexual things that appeal to us least. TMT, in contrast, allows for appeal to heighten negative reactions, since more intense sexual desire may feel more creaturely and therefore pose more of a mortality threat. So the question is, can we observe this kind of ambivalence?
Are anti-gays just gay men in denial?
The most famous example of apparent simultaneous sexual attraction and repulsion is Adams, Wright, and Lohr (1996). Adams et al. found that penile circumference increases in response to a gay porn film were greater in homophobic men than non-homophobic men, although all subjects rated themselves as maximally heterosexual on the Kinsey scale. However, erections don't always indicate sexual appeal, and Meier, Robinson, Gaither, and Heinert (2006) note an absence of replications, literal or otherwise, for this remarkable and notorious finding. Moreover, Meier et al. found that viewing times of gay porn and implicit associations of gay porn with positive words were either negatively correlated or not correlated with homophobia. And Mahaffey, Bryan, and Hutchison (2005) found that homophobia was positively related to enhancement of startle reflexes induced by gay porn. (An enhanced startle reflex following exposure to a stimulus implies the stimulus is aversive.) These findings make it hard to defend the extraordinary claim that anti-gays are just gay men in denial.
An ambiguous contribution to the Adams et al. controversy is Zeichner and Reidy (2009). Zeichner and Reidy, using a lexical decision task, found that exposure to gay porn caused positive correlations between homophobia and anger and homophobia and anxiety, but a negative correlation between homophobia and happiness and homophobia and disgust. The homophobia–disgust correlation supports Adams a bit, but I'd be hard pressed to draw an overall conclusion because it seems plausible that anger is being transmuted to disgust, or vice versa, between conditions, perhaps through a misattribution-of-arousal effect. On the other hand, the homophobia–disgust correlation is somewhat more damaging to the disgust theory itself.
Fertility and the menstrual cycle
Fessler and Navarrete (2003) examined how self-reported disgust at sexual-taboo violations (e.g., "You hear about a 20 year old woman who seeks sexual relationships with 80 year old men.") varied over the course of the menstrual cycle. They found that the more fertile the cycle phase that subjects were in, the greater the disgust. A better-known finding about the menstrual cycle and sexual affect is that sexual desire peaks around midcycle (Bullivant et al., 2004). The data of Wilcox, Dunson, Weinberg, Trussell, and Baird (2001), which Fessler and Navarrete used to compute fertility, indicate that this phase is also when fertility is greatest. We are left with the suggestion that sexual disgust and sexual desire peak simultaneously, which is the opposite of what the disgust theory would predict.
Attraction to disgusting things
As mentioned in the chapter on preferences, it's remarkable how many people are attracted to things that are painful or embarrassing or disgusting. To be clear, the disgust theory allows for individuals to find attractive what society as a whole doesn't, because sexual preferences are idiosyncratic (however much they're biased towards social norms) and sexual preferences determine sexual antipreferences. So same-sex attraction, for example, can be readily accommodated. Attraction to feces or other things that are intrinsically disgusting is harder to reconcile. The disgust theory would need to conclude that although sexual arousal tends to reduce disgust, disgust may not reduce sexual arousal—that is, sexual arousal trumps disgust. A concrete prediction is that subjecting sexually aroused people to some disgusting manipulation shouldn't much dampen their arousal. That is, although covering food with feces will certainly make it less attractive, the same should not hold for sexual stimuli. I don't think this has been tried.
The disgust theory is worth further investigation, but my money's on TMT.
Adams, H. E., Wright, L. W., & Lohr, B. A. (1996). Is homophobia associated with homosexual arousal? Journal of Abnormal Psychology, 105(3), 440–445. doi:10.1037/0021-843X.105.3.440
Bullivant, S. B., Sellergren, S. A., Stern, K., Spencer, N. A., Jacob, S., Mennella, J. A., & McClintock, M. K. (2004). Women's sexual experience during the menstrual cycle: Identification of the sexual phase by noninvasive measurement of luteinizing hormone. Journal of Sex Research, 41(1), 82–93. doi:10.1080/00224490409552216
de Jong, P. J., van Overveld, M., Schultz, W. W., Peters, M. L., & Buwalda, F. M. (2009). Disgust and contamination sensitivity in vaginismus and dyspareunia. Archives of Sexual Behavior, 38(2), 244–252. doi:10.1007/s10508-007-9240-x
Mahaffey, A. L., Bryan, A., & Hutchison, K. E. (2005). Sex differences in affective responses to homoerotic stimuli: Evidence for an unconscious bias among heterosexual men, but not heterosexual women. Archives of Sexual Behavior, 34(5), 537–545. doi:10.1007/s10508-005-6279-4
Meier, B. P., Robinson, M. D., Gaither, G. A., & Heinert, N. J. (2006). A secret attraction or defensive loathing? Homophobia, defense, and implicit cognition. Journal of Research in Personality, 40(4), 377–394. doi:10.1016/j.jrp.2005.01.007
Wilcox, A. J., Dunson, D. B., Weinberg, C. R., Trussell, J., & Baird, D. D. (2001). Likelihood of conception with a single act of intercourse: Providing benchmark rates for assessment of post-coital contraceptives. Contraception, 63(4), 211–215. doi:10.1016/S0010-7824(01)00191-3
Zeichner, A., & Reidy, D. E. (2009). Are homophobic men attracted to or repulsed by homosexual men? Effects of gay male erotica on anger, fear, happiness, and disgust. Psychology of Men and Masculinity, 10(3), 231–236. doi:10.1037/a0014955