Your grout turns dark after many years of dirt trapped in the pores of your tile and grout.  Don’t waste your precious time mopping and scrubbing with a toothbrush on your knees. This dirt cannot be cleaned up with traditional cleaning methods.  Tile and grout are notoriously difficult to clean.  Every homeowner and business owner knows that regular mopping, home tile cleaners and home grout cleaning methods just don't do the trick, especially if you're trying to eliminate stubborn dirt that has settled on tile surfaces or deep into grout lines.