Back to the German Shorthair I owned, he was an extremly ill tempered dog.
I could not hunt him with another dog, he would kill them and made short work of it I might add.
He would retrieve to anyone, however whomever was hunting with me that day better not step in my yard at home as he would go after them with extreme aggression wanting to bite them.
I always had any hunting partners wait in the truck when we got back to my place until I had him secured in his kennel.
He bit me once, paid dearly for that mistake and never made it again.
If I was not home and my wife would go out to feed him she never went in the kennel she would slide his food pan under the kennel door.
No offense but I'd have shot a dog like that. I don't allow aggression of any sort in my hunting dogs. Sure there's controlled aggression such as in properly trained security/shutzhund dogs but that's a whole different ball game and those dogs aren't aggressive till ordered to be. The kind of aggression you described in the dog is something that needed to be trained out of him and if that was not fixable he should have been destroyed for the safety of your guests and family.
When I'm taking dogs for training I watch closely for aggression. If a dog shows minor signs of aggression the cost for training goes up quite a bit because of the extra training it'll take to get rid of that aggression. If the dog has serious or hard signs of aggression I don't accept the dog for training because of the risks involved.
I've already shot two dogs that I owned because of aggression - one was a $3500 dog - fully trained and purchased from a hunter who had the dog trained with another trainer. Somehow between being fully trained and he age of 4 he'd developed some aggression issues but of course when I bought the dog that wasn't made clear to me. I got the dog home and he was fine with me but my kids couldn't go near him without him lunging and trying to bite them. Same went for my wife and my neighbors. After 2 months of quarantine and attempts to train the aggression out of him I put a .22lr bullet in his head and turned him into a $3500 flower garden.
The other one didn't cost so much - he was a pure bred lab that I bought at 18 months to train for a client. The contract was that I'd find/procure a young (but mature) dog and train it for the client who would then pay me for my services. $500 later I had an 18 month old purebred lab male with great hunting instincts. Sadly the moment I tried to put a leash on him he bit me. I tried again and he tried to bite me again. A few weeks more of trying to work with him resulted in another bite and he was added to the flower garden. I found a different lab that wasn't aggressive and fulfilled the contract - the client was happy.
GSP and other dogs aren't supposed to be aggressive by nature. That happens when something is either wrong with the dog's head OR something happened to the dog that turned it aggressive. Either way if it can't be fixed there is no reason to put others at risk of a bite and injury (or even death).
That said, lack of discipline and owner interaction will soon ruin them.
Lack of discipline and owner interaction will destroy ANY dog, big, small, working, sporting or otherwise.
Funny, when a toy dog gets bored and destroys something, it's cute. When a large dog does it, suddenly it's destructive.
There's no distinction in my book and shouldn't be in other people's books either. A dog that gets bored and destroys something is destructive. It shouldn't matter based on size - after all it did destroy something. Its not cute. It is however a curable problem because the problem actually isn't the dog - its the owner. The owner just needs to give the dog more attention, exercise and activities to keep it occupied. That and crate your dog whenever you leave it home alone unless its job is to guard your home while you're away. If that's the case you'd better hope your dog is well trained and even then leave him/her something to keep occupied with OTHER than the table legs, shoes, doors etc.