If it is actually porcelain, then by definition it is not "porus" (porous). Porcelain means not porous.
Not necessarily true!
Porcelain tile is a tile of high density - this is true. But when porcelain tile is made it is high-fired, this process causes microscopic pores to open and remain open. Not all porcelain tiles are true porcelain tiles and the actual quality of the tiles can vary. Some lower quality so-called porcelain can and does stain when applying the grout. Porcelain tile (true porcelain tile) has a water/moisture absorption rate of only .5% giving it one of the lowest absorption rates of any tile but it is possible to stain it.
Porcelain tiles with a high level of surface texture such as this tile can also be stained by clinging onto the grout products. The surface has a high co-efficient of friction rating that makes it more slip resistant but the trade off is the possibility of surface staining.