Mable does require a little more maintenance than other materials, but the results are worth it! Sealing is very important with your marble counters. the sealant will not make the tops stain proof, but it helps with repelling. Protecting your counters from anything acidic is also extremely important, if exposed to acid for long periods of time etching will occur. (vinegar, citrus, tomatoes, acidic cleaners etc.) Etching is a reaction that takes the polish off the marble and eats away at the stone.  A benefit to marble being more porous than other materials, is that it is easier to fix and stain can be removed most times with a poultice mixture.