The sensitivity of teeth could either be due to recession of gums because of gum problems or generalised wearing down of teeth or the necks of teeth exposed or worn out. The teeth have their own natural colour like our skin has and it may vary from person to person. Bleaching and scaling is able to remove superficial stains, which build up over the time due to food, coffee or tea intake. It is quite natural to have smell of food consumed in breath unless you rinse your mouth, after every consumption. Bad smell in the breath could also be because of impending gum disease, which needs professional help. Well, stick to the advice of your Dentist and I am sure he should be able to help you out.