you should drink them only when you make an intensive sport activity that last more than 90 minutes.
sport drinks are useful only when the body is not aware of the need for fluids. the sport drink gives the body all the energy that he will get from regular water and the reason that people drink it is because it's more tasty then regular water and they will drink it even though they are not thirsty.
it contains carbohydrates which help the body to stay awake but it will help only after a hour and a half.
so if you are not doing any sport drink orange juice - it will be healthier and cheaper.