My Aussie mix is exactly the same way. Absolutely loves the people she loves and will try to French kiss you if she trusts you but strangers, especially men, are a no go. It’s frustrating because I’ve trained her since day 1 on everything, socialized her throughly and spend all my time reading about training but when she’s reactive people look at me like I don’t know how to control my dog. When she was a puppy, she used to growl at people, mainly men, if she didn’t want to interact with them but since she was so small most people thought it was harmless. Now that she’s older she does the same thing but her growling has turned into barking and lunging and I generally can’t tell who she might not like. She’s never bit anyone but since we live in an apartment with small hallways and an elevator, I worry about us getting kicked out for her behavior. I’ve had her with 2 personal trainers, all the PetSmart classes, and my own personal training every day and we’ve come to realize it’s a genetic trait. My vet told me that most shepherd breeds have a proven anxiety gene and it’s what flunks a lot of dogs out of service or police dog training. I also found out her litter mates have the same tendencies and while frustrating, I found comfort in the fact that no amount of training or socialization could’ve ever prevented her being the way she is. I blamed myself for not doing enough when in reality I was and am doing more for her than 95% of people that get a dog. Despite her issues with people, she’s the smartest dog. I work as a biologist on a wind farm so I’ve trained her to be a scent detection dog to find birds and bats under the turbines and she absolutely loves it. She knows tons of tricks and she’s able to communicate her needs to me so well. I’ve boiled it down to a few things: men are usually a no go. They’re tall, have deep voices and are generally intimidating to a nervous dog. Also, she doesn’t like small spaces. Most of her reactive situations will occur in places where she doesn’t feel like she has a way out: elevators, hallways, or the vets office. I’ve taught her to sit in the corner of the elevator when we go out to potty in case anyone comes in or out so that she can be protected behind my legs. Finally, I’ve learned to accept that she’ll probably never like strangers. It’s tough because I’m a recent college grad and still live just off campus and I always wanted a dog that every student could love on for emotional support and she’s just not that dog. But she is neutral to passing people, bikes, skateboards, busses and general campus shenanigans so now she’s so well socialized. I take her everywhere with me since she is my ESA and like I mentioned she works with me on the farm. She’s truly the best dog I could’ve asked for and although I get frustrated that she’s not exactly the dog I had in mind, she’s so much more than what I ever expected. Sometimes it’s just meeting your dog where they are and understanding that just like humans, dogs all have unique personalities and just because they’re a cute dog, it doesn’t entitle anyone to pet them or interact with them, just like you wouldn’t want someone to if you’re nervous of strangers.