Pound's poem demonstrates the economy and power words have for us. It is devilishly short, but one could write reams on it. Look to the meanings and denotations of the words and you'll find your answer. "Apparition" according to dictionary.com means:
1. a supernatural appearance of a person or thing, esp. a ghost; a specter or phantom; wraith: a ghostly apparition at midnight. 2. anything that appears, esp. something remarkable or startling 3. an act of appearing; manifestation.
The first two meanings would suggest a darker aspect of the poem. i would suggest the poem hints at darker things and darker aspects of our existence.
The first two meanings would suggest a darker aspect of the poem.