Normally I'd say not to polish unless the marble is so beat that it is trash and it would be nice enough to warrant the time or expense if it was polished. I polished this one by hand. It would never be appreciated again in the condition it was in, so I polished it and although now it's in polished condition, it can be displayed and appreciated. So I think it was worthwhile. For a common latticino core, not worth it IMO but someone else may have a different opinion. Which is worse, polishing it or tossing it in the trash? Either way it's never going to be an original surface top shelf marble again, so why not make it at least beautiful again?