Flooring Tile - Grout has Whiteish haze in spots

I tiled 2 bathrooms over 2 weekends. Then I grouted both on the same day the following weekend. This weekend I cleaned the tiles. One bathroom came out very nice, the other has a white haze over the tan grout in more spots than I am comfortable with. I put 3 coats of sealer down in a spot that will be covered by the vanity and there was no improvement to the white haze. Before I seal the whole room, can someone tell me the best way to un-haze the grout?

Try some Sulfamic acid crystals mixed in water and spread over the grout and tile. Let sit for a few minutes then use a stiff bristle brush to agitate the areas with the haze. Clean and rinse with water.