My wife and I have rescued and placed dogs of all sorts for quite a few years. Just like children in the foster system, they all come in with their own individual issues that need time and patience to heal.
Its not always easy to get the animals to adjust. Whenever we bring in a new rescue the whole pack has to examine their place on the totem pole.
Like Kurt, we have had to turn down and seek placement for some that were too disruptive.