It has recently come to my attention that I have been neglecting the grout in my tile floors. Really, I have always assumed that the slight discolorations here and there were character. Not so, a friend has told me. She has her grout professionally cleaned every six months or so. Unless your grout is white, you don't want to use chlorine bleach as it will discolor the grout, resulting in a mess that is worse than before. Before you begin your scrubbing, you will want to vacuum your floor thoroughly. Then get out your scrub brush.