ceramic tile cleaners pour equal amounts of epsom salts and liquid dish detergent to form a paste to clean ceramic tiles.
in a spray bottle put 1 qt. warm water. Add 1/4 cup baking soda, 1/4 cup white ammonia, and 1/8 cup white vinegar. Vinegar and baking soda mixed causes a chemical reaction so mix this over a sink as it can be very messy.
If your white grout isn’t so white anymore you can paint it with Wite-Out white correction fluid for typing errors. Just paint it on the grout to cover up the stains.