Rambo

Whenever someone mentions the movie Rambo: First Blood I immediately call to mind the scene where he is camouflaged in the mud and as a Bad Guy walks past Rambo emerges from the muck to dispatch said villain. The Ridgebacks, thankfully, rarely feel the need to immerse themselves in mud but they do often manage to disappear into their environment. And it's not even like they try to blend, they just do.

If you're not looking for the dogs in the field you can rarely see them. Surprisingly, even in winter on a white background, they manage to disappear as well. In the summer, it's a bit of a hassle trying to get nice photos when the surroundings are constantly over powering the focal point of the photo, although it might help if I had a better camera, one day my DSLR will come.

Then again, if you are a black dog in light grass it's hard to blend, but put her in the shade, step back a few feet and she becomes invisible.  Unfortunately her breed is not typically inclined to stay unnoticed which is why she is rarely found standing in one spot long enough to disappear.