You can make generalizations about any breed, but there will always be exceptions. Some of it is just the individual dog, but a lot of times it might just be a bad fit between the dog and the people (or other animals) involved. Some dogs are easy, others need a little more work in terms of behavioral training and daily exercise.

I've known some really good rotties, pitt-mixes, huskies and malamutes. I know that their good behavior has everything to do with the environment and training that their people provide for them.

OTOH I have yet to meet a well-behaved golden retriever.

When meeting any new dog, regardless of size or breed, it's always a good idea to ask the owner if and how you may approach their dog.