Do you like drinking tea or coffee but hate the stains in the bottoms of your cups? Clean tea and coffee stains from the bottoms of your cups by sprinkling in a bit of baking soda or salt. With a wet soft cloth rub the baking soda or salt around on the stain and watch it quickly go away!

You can also try the following tips that were sent into the site.

Remove stains that build up in a tea (or coffee) mug or cup just dissolve a tablespoonful of soda crystals (aka washing soda) with warm water and leave to soak for an hour. The brown film will then simply wipe off. Not as hard work as scouring and doesn't leave a taste like bleach does (and it's non-polluting!).

Easyways Says:- Washing soda is not baking soda. You find washing soda on the selves where your get your laundry detergent. It is an old fashioned product used for laundry. If you hunt around you should be able to source some.

Also

To clean coffee/tea stains out of mugs, just rub a little 'whitening' type toothpaste on the stains. It cleans them off instantly.