I watched a Japanese TV program about “Senkou線香: incense for Buddhist”. They smelled each senkou sold by each famous temples in Nara and Kyoto.
The perfumer of senkou explained some interesting things.
The words “sweet”, “sour”, “spicy”, “bitter” and “salty” are used to describe the aroma.
Sniffing lemons is good to reset the smelling sence, olfactory system.
The reason why monks burn senkou is that in some Buddhism group said after people died they eat aroma called “jikkou食香”, for the 49days.
Blending more than 30 different smells in one senkou such as Sandalwood, Star anise, Cinnamon, Frankincense and “Kyara: 伽羅”. All of which are also aromatherapy essential oils.
However I have never heard Kyara, a hand size piece of wood is as expensive as a luxury car, sounds very interesting to me! I might do further investigation.