Smelling coffee beans between fragrances resets your nose and clears olfactory fatigue
The coffee bean practice is widespread at fragrance counters and largely unsupported by evidence. The proposed mechanism — that the compounds in roasted coffee neutralise or displace the olfactory receptor saturation caused by fragrance molecules — has not been demonstrated in controlled olfactory research. The most likely explanation for any perceived benefit is that the strong, familiar smell of coffee simply distracts the brain from the previous fragrance impression, creating a subjective sense of reset. This is not the same as neurological olfactory recovery. The actual mechanism for olfactory reset is time and fresh air.

WHAT TO DO INSTEAD
To reset between fragrances: step outside or to a neutral-smelling environment for 2 to 3 minutes. Breathe normally. Smell the back of your own hand (unscented skin) or a clean sleeve. Do not use coffee beans, scented candles, or other strong olfactory stimuli — these replace one competing scent with another. When testing multiple fragrances, test no more than three in a single session. Testing fatigue accumulates and your evaluations become increasingly unreliable after the third. Use blotter strips first. Apply to skin only the formula you are seriously considering.