I know what the verb leer means:
to look at someone in an unpleasant way that shows that you think they are sexually attractive
[Longman Dictionary of Contemporary English]
What does 'leering' mean in this context?
The edifices were in a state of decay-shutters torn off, roofs crumbled under the weight of heavy snows gone by, windows dusty and leering.
from'Night shift' by Steven King