Now on to dogs:
We all know the range of appearance in domestic dogs. Some domestic dogs even bear a superficial resemblance to wolves. Perhaps some of those individual breeds have had some recent (past couple of centuries) outcrossing to wolves. GSDs are possibly one of those breeds.
Let's look at pictures of feral dogs, shall we? If they are descended from wolves, ferals should start to look wolfish, coyote-ish, or huskyish.
A picture of a Puerto Rican feral dog taken from a us gov. website:
El Yunque National Forest - Wildlife Facts
The dingo, arguably the most famous feral dog population in the world. Who have not once produced a remotely wolflike individual, in all the centuries that they have existed.
Trapping feral dogs in Mexico, deep in jungles far from any human villages. In other words, these aren't F1 or F2 stray populations.
Manuel Weber: First feral dog in Calakmul / Primer perro feral atrapado en Calakmul
DNA research on village dogs in Africa and Asia undermines the wolf = dog theory:
Village Dog Project
http://www.nytimes.com/2009/08/04/science/04dog.html
One striking thing, about ALL the feral dogs is that NONE of them look like wovles. They are all yellow/red, prick eared, DOGS.
They all look like the most ancient breeds we know, the pariah type dogs common in india, the middle east, africa. Dogs like the basenji, the yellow Carolina dogs, and Canaan dogs. It is likely, given that the wild ancestors of many domestic animals (cattle, horses, sheep, goats) are now extinct, that the ancestor of the dog was a yellow canid who is now extinct in the wild, except for feral throwbacks.
This article is a fascinating read if you're willing to have an open mind:
Darren Naish: Tetrapod Zoology: Controversial origins of the domestic dog