Mix 1 to 2 tablespoons each of baking soda and distilled white vinegar or apple cider vinegar inside your coffee mug. Add 1/4 cup of hot water. If cleaning a stainless steel, thermos-style mug, close the lid and shake vigorously. The baking soda acts as a stain eliminator, while the vinegar serves to deodorize.
Scrub the entire inner surface of your mug -- not just the stains -- vigorously with a toothbrush or sponge. Scrubbing all the surfaces ensures complete removal of any lingering coffee odors.
Rinse your mug with hot water. Allow it to dry. The vinegar scent may linger while the mug dries, but will disappear after a short time.
Remove Stains from Fabric
Add 1 teaspoon of white vinegar to one quart of water and mix well. Scrub the coffee stain vigorously with a cloth or sponge until the stain breaks up and disappears.
Place your clothing or fabric in a conventional washing machine if the vinegar and water procedure fails to thoroughly remove the stains. Add 1/4 cup of white vinegar, along with your preferred laundry detergent. Do not use bleach, because it will react negatively with the vinegar.
Place your clothing or fabric in direct sunlight to dry. Use a commercial dryer if no sunlight is available. It is essential that the clothing or fabric dries completely to prevent mildew from forming.