The Quiet Type
Basically, most dogs have two bona fide reasons to bite: 1. Because they are dogs and that's what dogs do and 2. Because by and large, people are not very nice to them.
When dogs are upset or frightened, they don’t call a lawyer, or write a letter of complaint, they simply growl and bite. Ironically, in the rare instances when a (usually) fearful dog does follow through, he is often accused of unpredictably biting without provocation — without warning and without reason. In reality though, there were most certainly many good reasons for the dog to bite and he most certainly gave numerous warnings, even though the warnings may have been too subtle for most human observers.
Many dogs do, however, bite with little threat or warning, but this has very little to do with aggressiveness. On the contrary, the vast majority of dogs bite because they are fearful, frightened, unsocialized, and/or lack confidence. A bite might be expected if the dog were cringing, or snapping and lunging, but often the dog's standoffish demeanor is the only overt warning. And of course an unsocialized sleeping dog may bite if disturbed or frightened. Other dogs bite due to uncontrolled rambunctiousness. The dog may be in a decidedly happy frame of mind and is only doing what he did as a puppy, because no one taught the puppydog that unsolicited playbiting was unacceptable. Now the adolescent dog's playfulness is out of control and he hurts people. Thus a dog may bite with nary a growl. Indeed, the biting dog may be playfully wagging his tail!
There is an additional, quite insidious reason for a dog to bite without warning. Originally the dog would growl whenever he was upset. Although people heard the growl, they did not listen to what the dog was saying. The dog was upset but no one paid heed. Instead they punished the dog for growling. The dog now had two reasons to be upset, the original reason and the fact his owner is angrily bullying him — and so, the dog growled more. Unfortunately, the level of punishment was increased until it effectively inhibited the dog from growling. The dog no longer growled, but he was still upset, in fact, very upset. Now we have the equivalent of a time bomb without the tick. The dog is doubly upset but no longer shows it, because the owner systematically punished him for trying to communicate his feelings. By all means instruct a growling dog to shush but ALWAYS investigate and attempt to resolve the underlying cause.