Okay so maybe for my second post this may be a bit lame, but seriously you have to try this.
If you have strawberries in your fridge go and get one, NOW. Afterwards, get a sweet look at your chompers and accept the colour they are right now. Now, rub the strawberry all over your teeth for at least a minute. Rinse with water and look in the mirror again.
They are like 10 shades whiter. If this didn't work for you then obviously your teeth are already clean enough.