My guess is you've already gone but if not, a couple things to think about when you see her -
1. What you see at the shelter is only a snapshot of that dog. Their personalities can be squashed down quite a bit with the stress so any temp test may or may not be accurate. I've seen very mellow dogs turn out to be energetic and very frantic or stressy dogs turn out to be quite relaxed. Dogs with no interest in toys who are really toy fanatics etc etc. It's tricky.
2. Most shelters really don't know how to assess things like prey drive or dominance or to put any observations in the context of what's normal for that breed. That is, "high energy" just means energetic relative to other dogs they deal with not necessarily what we GSD people might call high energy for a GSD. Same thing with "nervous", "shy' or "protective." Almost ANY GSD in a shelter is going to come across as "protective" at the shelter and they may call that dominance but that doesn't really mean anything. As a breed, GSDs tend to be on average kind of barky and to react defensively in a shelter environment so how she compares to all the huskies or Beagles at the shelter probably isn't going to tell you what you want to know about her specifically.
Rather than using words like "dominant" or "submissive" you may do better asking them specific questions like "Does she eat before the other dogs or hang back?" "When she plays with other dogs, what does she do?"
So... just do the best you can to see what vibe you get from her and how you connect and take anything you hear with a grain of salt because it may or may not be accurate - and that definitely includes any info from the surrendering owners if she turns out to have come from a home. Adopting a shelter dog is a bit of a question mark but it's also incredibly rewarding.
All my current dogs are shelter or shelter via rescue finds and even though each has held a few surprises (as do many of my fosters) they're all wondeful dogs and I'm very happy I decided to pull them. Best of luck and thanks for considering this pup!
