ريح الفم والعنبر
Fragrant breath and the scent of ambergris.
The shared aspect here is fragrance, detected by smell. Sensory status does not require the compared things to be visible; the relevant likeness belongs to the olfactory sense.
Distinguish an object from the property perceived in the comparison. A perfume bottle can be seen, but if the comparison concerns its smell rather than its shape, the analysis must attend to smell.