This image has absolutely no deeper meaning.
I found this nice and very detailed free model of a NY city block (I don't know, if this particular block really exists?!) at CG Trader. Some nice stuff there. But it was in 3ds Max format, so unfortunately not useful for a lot of people.
I collected some other free objects, used the fabulous NWDA dirt pack and created some models myself.
As far as I remember this is my third image, in which excrements play a role... Fred is a nicely detailed scan from
Artec3d.com.