Morning All,
1964 we bought a house that had 6 children living there. We had 3 and added 2 more during our stay. When we put it up for sale I used shoe whiteing once over in all the grout seams. The people that bought the house asked if we had put in a new bathroom. BTW, we had 4 little boys and you know how that goes!
My recommendation is baby/nurses shoe whiteing.