How does the receptor un-lock? What happens to the previously airborne molecule, now coupled to the cell with the receptor, to make that receptor open to receiving again?
Maybe a naive question, but could that help explain why your sense of smell adjusts? If there is a finite number of receptors and they require excitation to trigger the sense of smell, it stands to reason that saturation would dull the sense of smell.
Visit somewhere smelly like a farm and your sense of smell is blown away by what you would call pretty odiferous smells. Stay there a few days and the smell seems to lessen. I guess the receptors get blasé about these molecules to help you cope with your new environment. So I would go with the idea of saturation.
I imagine that acclimation phenomenon is neurological, as the same thing happens with background sound
I'm going with "washed out by snot"
Brownian motion?
Forgive me, but that's not what Brown-nosing means.