Someone's Bark Is Worse Than His Bite
You know the situation: you are walking down a street and a dog
runs towards you and begins to bark. You are frightened half to
death - but then the dog wags his tail and licks your hand. When
you've recovered from the shock you realize the dog's bark is worse
than his bite. People too sometimes 'bark' but in time we learn
they are not always as frightening as they seem. "Dont let Paul's
shouting fool you. His bark is worse than his bite."