Bad habits are harmful to teeth

Potato Chips

The bacteria in plaque will also break down starchy foods into acid. This acid can attack the teeth for the next 20 minutes -- even longer if the food is stuck between the teeth or you snack often. You might want to floss after eating potato chips or other starchy foods that tend to get stuck in the teeth.
Constant Snacking

Snacking produces less saliva than a meal, leaving food bits in your teeth for hours longer. Avoid snacking too frequently, and stick to snacks that are low in sugar and starch -- for example, carrot sticks.
Drinking Red Wine

The acids in wine eat away at tooth enamel, creating rough spots that make teeth more vulnerable to staining. Red wine also contains a deep pigment called chromogen and tannins, which help the color stick to the teeth. This combination makes it easy for the wine's red color to stay with you long after your glass is empty.