I perceived the aura of stench from a certain woman who later joined a group of sirens, and the stench emanated from her wherever she went for a period of several days. The spirits said that the reek was almost lethal, but still the woman herself did not smell it at all.
Sirens have essentially the same foul smell, since their inner depths are revolting, although their outer looks are mostly attractive and fetching. For more about them, see Section 831.
Surprisingly, sirens in the other world catch on quickly to everything there and see how things stand better than others do, even in regard to doctrinal matters. Their whole focus, however, is to turn what they learn into magic and seize power over others. They enter into good people’s feelings by a pretense of virtue and truth, but their nature is nevertheless as described.
This shows that doctrine is worthless unless we become what it teaches us to become—that is, unless our goal is to use it in our lives. Besides, hellish spirits count among their number many people who displayed more skill at doctrinal questions than others. People who have lived a charitable life, though, are all in heaven.
I talked with some spirits about the sense of taste. They said they had no sense of taste but something else that allowed them to recognize flavor, which they compared to smell, although they could not describe it.
This recalled to my mind the fact that taste and smell come together in a third faculty, as can be seen from animals, which find their food by scent. The scent reveals to them whether a thing is their proper food and good for them.
from Secrets of Heaven, Volume 2, Sections 1515, 1516