Bark Or Not, What Shall I Do?

I am in a big confusion. I don’t know how others are managing this. A well-dressed stranger is coming. He seems to be a gentleman, but these days gentlemen are creating problems! Anyway, let’s come to the topic. Some dogs barks at anything and some prefer to remain silent until a stranger crosses the limit. 

Hey, he is a total stranger, let me watch him closely every bit of his action to decide to bark or not. You know there is a saying in the dog community, think before you bark! I hope everything will end in a friendly manner. What’s your suggestion?