Hidden Ovulation

There's this odd assertion that the ovulation of women is "hidden". Understandably, women do not develop all sorts of odd symptoms like swollen red butts when it's around that-time-of-the-month. However, it would be too hasty to assume that ovulation is hidden just because humans (mainly men) are incapable of sensing its coming. I think even a human would be able to scent the difference when someone is about to ovulate. If not only the sense of smell, then perhaps the weird feelings that pop out of nowhere when you're actually experiencing it? Or the heightened senses and certain friskiness? Well, perhaps some are just unwilling to admit it to themselves...