I learned recently why it is that we are generally incapable of smelling ourselves. It turns out that the human nose has a built-in timer that limits how long we can detect smells. If you walk into a room and sniff somebody’s nice perfume or some fresh-cut flowers, or drive past a flattened skunk or a malodorous oil refinery, your brain will register the new scent— but within a couple of minutes, you will stop noticing it. The brain will put this olfactory data aside so it can be available to recognize and focus on new information.
In caveman days, I suppose this was a life-saving defense mechanism that kept Cro-Magnon Bob from being surprised and devoured by a saber-toothed predator while he was half-way through his delicious-smelling mastodon steak dinner. In the modern office, it merely saves you from enduring all day the aroma of Guy-Who-Eats-Way-Too-Much-Garlic, because your brain is naturally dulled to his scent fairly quickly. And, it means that when you are working out at the gym or industriously digging up the garden, your nose quickly adjusts to your own growing body odor so that you are the last one to know that you reek.