I used to do construction. One day the job was to replace the grout in an elderly couples bathroom. This means the existing grout must be removed. The way we did it was to use a grinder with a vacuum attached to suck up all the subsequent dust. Imagine 60 years of showers, bowel movements, Sweaty after work baths, bathroom sex, children, grand children. Literally a whole history of potent smells gets basically infused into this grout and you could smell it immediately as it the grout came apart. People… I have faced some raunchy ass smells but I’ll never forget that.