My grout cleaning service is the most comprehensive you can find. After doing hundreds of grout jobs I have found that spraying the grout with an acidic tile cleaning solution and then scrubbing every grout line with a V shaped brush causes the grunge to lift prior to vapor cleaning. After the tile looks clean I then vapor and extract utilize truck mounted high power machinery. Don't let anyone laugh at you they cannot run the high strength chemicals directly through their tool nor would it dwell or be scrubbed so steam only co.'s are not nearly as complete.