Okay I've officially tried it all!!! Commercial cleaners, oxi-clean, toothpaste, even prayer :O) and NOTHING has worked. This house is old and it seems that my grout is more of a cement consistancy than a grout consistency or that it is just so old and dirty theat it looks like cement! I'm unwilling to replace all the grout and tile in the bathroom as this is a rent house, but there has got to be a way to get this stuff clean!!! HELP!!!