I recall reading a guidebook that instructed the reader NOT to smile, the author stating that the French will think you are a bit light-headed or off if you smile. I immediately imagined a bunch of people with surly expressions, doing their best to overcome their better nature, disappointed when people were surly back to them And actually, my experience has been that the opposite is true. A smile is an act of kindness, and people, even the Parisians, often have a positive reaction to kindness. So, may I suggest an experiment? Smile when you say Bonjour Madame, Bonjour Monsieur, before asking a question. Smile and say Merci when someone does something for you. See what happens.