I think some breeds have certain character "tendencies".  Doesn't mean that all dogs of a certain breed do it but that a large number do because of their breeding/job they were bred to do.  I generally don't judge a dog by its breed but I have yet to conquer my fear of GSDs.  I have only been around a couple of GSDs and they weren't well adjusted but that was due to the owners, not the dogs.  I see them as protectors which makes me nervous.
Back to the topic:  Our older (little) dog will start barking but we immediately intervene and she stops.  Thankfully, she doesn't do it very often.  Our younger dog doesn't bark unless something really scares her and no amount of discipline can correct that.