[yatrahnualenu]

ok.. I am just following your logic here.. if you actually think that you could be causing dogs to get so messed up to be aggressive towards humans..how is it a good idea to take a dog deemed adoptable and mess it up to the point where it may lose its chance to be adopted?
Trying to prove to yourself that you are able to raise a dog without issues is not a good reason to own OR to foster. And it has a high likelihood for failure. Foster dogs can definitely develop issues while being fostered, independently of how they were cared for.
Also, doubting your ability to raise the dog to turn out OK will make you doubt each and every step in the dog's training .. which will make for inconsistencies and an unclear vision of how to achieve your goal. For a dog that already suffered from abandonment and possibly abuse, this is not helpful at all.