Shower grout is one of the harder items to clean in a home. One reason for this is that grout is porous and so dirt and other discoloring agents can go deep into the grout. A second reason is that there are several ways that grout gets discolored. It could be from mineral deposits, from soap scum or body oils, from mold, or from some combination of the three. And each source requires it’s own cleaning solution. But with care and some experimenting that discoloration can often be remedied.