Some dogs don't care about treats, and some don't care about toys. Well, if you really need a treat and nuked hot dog won't work, try bacon. But I had such a bitch who could care less for treats or toys. But I she would walk a tight rope for praise. I had to totally train her using nothing but praise.
They are all different, you just need to find something that motivates her. I don't think a private trainer will help much for SSA, frankly. But I think taking your GSD to classes and working with her on a daily basis those things you are learning in classes, well after the classes are over, you might be in another place in your relationship, a better place. But don't stop there, sign up for another set of classes. It is a great idea to get her a good foundation.
Here's the thing, a dog with training may be better at doing what you want, and looking to you when in situations where she is uncertain. But if you still need to rehome the dog, a dog that can sit and down, and heel, and has demonstrated that she can be worked around other dogs, and people might be a little easier to find a good home for. A good goal would be the Canine Good Citizen Test.
A dog that is no longer a cute sweet baby puppy needs every thing possible in their favor to find a good home. Everyone expects an eight week old puppy to jump up, and to nip, and to have accidents in the home. A nine month old puppy that jumps up, can't sit or down, pulls you down the street, barks and lunges at other dogs or people, is going no where fast.
Training, just a little training can make the difference in so many cases, as to whether a dog lands in a shelter, and then on the euth list, or if a dog gets a nice home. Part of the cost of dog ownership is training. No, not everyone can afford a behaviorist/professional trainer to work with just them, but everyone who owns a dog ought to be able to come up with 75 - 125 dollars in six or eight weeks to take the pup to school.
It is true that people can train their dogs themselves. Some of us go to classes for the distractions of other dogs and people who are working with them. Some go because they want to fine tune stuff, and a trainer can see stuff about our body language and dogs reactions to it, that we simply cannot see. And some of us need to start from Go, learning everything from the beginning.
Find a good trainer in your area, and sign up for classes.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC