I used to be on this everlasting quest to find a good grout cleaner. As you'll see in some of the pics, I had given up on that quest long ago and decided to let the grout just become a constant dark brown instead of the light tan it was originally. I had tried every product and concoction out there. In fact I had tried everything I could think of, short of paying a professional. So one day I saw a pic on Pinterest of a floor with half clean grout and half really dirty grout. I wasn't sure it…