Dhaka's supply water is mineral-heavy, so a hard white layer builds on taps, showers and the rim of the commode. Scrubbing does not shift it, because it is not dirt — it is scale, and it needs a descaler at the right acidity, one that will not damage the tiles or the fittings.
We work in three passes: descaler applied and left to work, then machine-brush scrubbing of grout and floor, then a hospital-grade disinfectant. The real source of the smell is usually the floor drain and the exhaust fan — we clean both separately, which is why the smell does not come back a week later.
For tenants: a deep-cleaned bathroom before you hand back the keys makes the deposit conversation considerably shorter.