I understand the before & after photos in this post are not life shattering.  Truly, I do.  But for me,  even slightly dingy grout can make an otherwise spotless bathroom look so dirty still.  Clean grout  just makes me feel... happy.  I used two, cheap old ingredients.  Baking soda and vinegar.  I poured baking soda into the grout lines, and then sprayed vinegar on sections at a time and used a grout brush and scrubbed a dub dub away.   

It feels good to know I can clean yet another dirty sector of our home with cheap natural ingredients!