Grout lines can retain soil differently than the surrounding tile, and routine mopping may not remove contamination embedded in the grout surface. Residue and dirty mop water can also leave floors looking dull.
Grout is porous and recessed, so it traps soil.
Dirty mop water settles into grout lines.
Soap residue attracts dirt.
Kitchens and entries darken fastest.
Deep cleaning removes embedded soil, and sealing can slow it returning.
Deep Clean Your Tile & Grout: 410-979-2355