Use Clorox toilet cleaner with bleach to clean grout.... I tried this today and it worked like a charm!! My floor hasn't looked this good since I moved in!...LOTS of other Great Tips on this site and tons of eye candy!!!
Cleans grout, tile, stainless pots & pans, oven (inside & out), glass (including windows & soap scum off shower doors), car rims & mufflers, only thing it can't be used on is marble. Very little scrubbing & it cost less than 2 bucks!! When vinegar & baking soda won't work this stuff definately will!