As Redpunter said earlier (and it's been discussed on UKP before), beware the sense of smell of your OH.
I think some of us are more tuned in to our sense of smell than others, but you can probably multiply that ten-fold with a woman, especially if she's already suspicious.
I'm one of those guys (in touch with my feminine side, who knows
) for whom the sense of smell is very important, a woman has to smell right to me (I'm talking underneath the perfume and other masking shit that modern woman covers herself with these days).
In the post-coital haze with my ex we would be nuzzling, and she would actually say
you're sniffing me aren't you? We joked about it but I was, and so was she. Smell is our hidden sense, the one we ignore and forget about, but there's olefactory processing going on in your head, and especially a woman's head, without you even knowing, deep in the subconscious. For a woman, if things don't smell right her radar will be going off even without her thinking.