These pictures are of an installation gone bad. These tiles were soaked in water before installing them in an effort to keep the grout from absorbing into the tile during the grouting procedure. This process leaves too much moisture in the tile. These tiles were also sealed the same day they were grouted. This is a common occurance when the tile setters seal the tiles themselves. Saltillo, or any other porus tile, must be 100% free of moisture BEFORE sealing. Sometimes this may take a couple of weeks to be completely dry. The installer just wants to finish the job so he can get paid. That means your floor gets sealed before it’s dry. This traps all that moisture in the tile. While this is an extreme case of trapped moisture, a lesser case will appear to have a cloudy, dull, or streaky appearance. The sealer will eventually start to peel off. The cost to have a floor completely stripped and re-sealed can be 3- 4 times that of the the cost to properly clean and seal the same floor from the beginning. Moisture damaged can also be caused by leaks, floods, cracks in your grout or in the understructure of the tile, or cleaning with chemical that are too strong for the sealer to withstand.