For a while after we moved into this house the shower stall looked fine, but then the grout lines -- especially those between the edge of the floor and the bottom of the walls -- started looking dirtier and dirtier.
The usual shower cleaning products did not do much, nor did undiluted bleach straight from the bottle.
We thought of redoing the shower with plastic or fiberglass panels, but it's significantly smaller than any standard off-the-shelf units. No doubt we could get a custom liner made, but probably costing more than we would be willing to spend.
I've just started attacking the grout with a grout saw, with the intention of regrouting those joints, but it appears that the previous owner used silicone caulking compound over the existing grout along those edges. This complicates cleaning out the crevices. And even where I've managed to clean out the old grout and caulking compound, everything is still black, and even straight bleach seems to have no effect.
Any suggestions about the best way to deal with this?