Sniffed alone, the underarm odors smelled equally strong to men and women. When fragrance was introduced, only two of 32 scents successfully blocked underarm odor when women were doing the smelling; in contrast, 19 fragrances significantly reduced the strength of underarm odor for men.
Not only were women better smellers the men, but male odors were harder to block than female odors. Even though underarm odors from the two sexes didn't differ in how strong they smelled, only
So women have a better sense of smell, and, they do not smell as powerfully. Here's the original paper, Cross-adaptation of a model human stress-related odour with fragrance chemicals and ethyl esters of axillary odorants: gender-specific effects:
The human axillae have a characteristic odour that is comprised of or generated from a mixture of C6-C11 normal, branched, hydroxy- and unsaturated acids (and other compounds). We used ethyl esters of one of these acids and a palette of fragrance compounds (tested individually) to evaluate the effectiveness of these chemicals to reduce the overall olfactory impact of a model of human stress-related odour (SRO) by cross-adaptation (adaptation to one odorant can reduce sensitivity to other odorants). Sensory volunteers provided hedonic and intensity ratings of the SRO and of each of the potential cross-adapting agents prior to 2.5 min of induced olfactory adaptation to each agent. Across adaptation, possible cross-adaptation was evaluated by intermittent evaluations of the perceived intensity of the SRO. We determined that some potential cross-adapting agents did reduce the impact of the SRO; however, the same chemicals were not necessarily effective for male and female SRO. Indeed, the list of effective chemicals depended upon the gender of the donor of the SRO and the gender of the sensory volunteer, suggesting a gender-specific response to both the SRO-stimuli used and the fragrance chemicals used to cross-adapt it
That's a mouthful. But suspect that the researchers are trying to hook into the work which shows the correlation between MHC, odor and attraction. But I wonder if there's a straightforward non-adaptive developmental explanation to this? I know that testosterone can have all sorts of deleterious physiological consequences (e.g., depress the immune system). Looking at individual differences among women might suggest possibilities.
The idea that that it is not adaptive for testosterone to suppress the immune system is a controversial idea, and may I say, on its way out. It is probably an adaptive reallocation of energy towards different tasks (say, aggression).
If there's a sex difference, it probably means something. Either it's more adaptive for females to be less smelly or it's more adaptive for a male to be smelly. Either way, it's probably not a spandral.