How does Martin Millar use imagery in The Good Fairies of New York?

Imagery:

Every park was laced and ribboned with makeshift plastic tents and stinking blankets rolled up as sleeping bags.

"The black fairies lived, unseen by any humans apart from a few wise old women, in a small park on 114th street. The park was in disrepair, uncared for by the city authorities, but it was well known for its air of peace and very rarely did anything unpleasant happen there."