I certainly wouldn't discard a piece of pottery just because it smells. As Sasha says, you can boil it for sterility, unless the relevant bugs crept in from a Yellowstone hotsping or a deep-ocean thermal vent. If you want to clean out the pores complete, just let it sit with warm, dilute bleach for an hour. Then boil it in dilute tea solution to neutralize any residual bleach, and start again.
If the bad smell isn't actually affecting the taste of tea, who cares anyway? All true gastronomes know that the finest taste in the world is durian, whose accompanying smell may be the worst: a living (though it smells long-dead) embodiment of Taoist perfection.
-DM