We have 2 dogs. One we got as a 9 week old puppy and he honestly has never been any trouble. Clean in less than a week and never really bitey. Also have never chewed anything. We still have the toy lamb his breeder gave us 7 years ago and it looks new!
The other one was a rescue at 7 months. He had been abused and never socialised at all. He had been kept confined in a barn, never seen trees, grass, birds, cats etc.
Because he was never socialised and never saw anything really other than the arsehole who owned him and the inside of a barn he is terrified of everything. His way of coping with this is to bark at everything and everyone. He is fairly large so looks quite scary although he has never tried to bite anyone or even growled at other dogs, people etc.
We have had him 6 years and although he is a bit better he is still a nightmare to walk and can be a pain indoors as he will destroy anything if it is left within his reach.
I have had quite a bit of abuse from people especially other dog walkers because he barks loudly at them. I always try and avoid other dog walkers and keep him close to me but still people shout at me and say I shouldn't be walking a vicious dog!
We moved just to be somewhere quieter so that we could hopefully walk him without meeting 20 other dog walkers in even a short walk. Only 1 dog sitter is willing to look after him and she lives a 2 hour drive from us so we can never both go out for more than 3 or 4 hours at a time and holidays are a rarity
I have shed many many tears over him but would never ever get rid of him.