<human>:  What is the best way to clean dirty tile grout?
<bot>: The best way to clean dirty tile grout is to use a grout cleaning solution of vinegar and baking soda mixed together. Apply the solution to the grout and scrub the area with a toothbrush or grout brush. Let the solution sit for a few minutes and then rinse with warm water. Repeat the process as needed until the grout is clean.