How does China Mieville use imagery in Perdido Street Station?

Imagery:

"New Crobuzon was a huge plaque pit, a moribific city. Parasites, infection and rumor were uncontainable. A monthly chymical dip was a necessary prophylactic for the Khepri, if they wanted to avoid itches and sores."

Militia-pods streaked through the heart of the city to its outlands, the cables that held them twanging and vibrating like guitar strings hundreds of feet in the air. Wyrmen clawed their way above the city leaving trails of defecation and profanity. Pigeons shared the air with jackdaws and hawks and sparrows and escaped parakeets."

"The body of the creature was a tangled, welded lump of congealed circuitry and engineering."