The Difference with a German Shepard is that it usually very apparent when you have a bad one like this. They are usually consistent in how they behave.
I’d be curious about the history of the pooch. If I was a babysitter, seeing many people who were strangers to me, I wouldn’t want to bring along any dog. One wrong cue by the dog, and the situation could turn quite ugly. A dog that had known the baby from birth as part of family would be less likely to be dangerous. Dogs are loyal creatures rather than moral ones, and may do things that to humans are quite stupid, like think that a baby is a hazard to the babysitter and needs to be eliminated.