Often silver and silver plated teapots can become very dirty inside, especially if Tannin build up has been left for an extended period of time. A good trick to remove this dirt is to wrap alluminium foil aroud the prongs of a fork and place this, prongs down, into the pot. Add a denture cleaning tablet such as Steradent, and then fill the pot with hot water. Leave this solution to bubble away overnight, and the next morning empty the pot out. You should now find that the teapot is cleaner than before, and any stains still inside should easily wipe off with a cloth. If stains persist, repeat the above steps.