It Can Break Down Limescale
Similar to the effect spoiled milk has on jewelry, it can also help breakdown limescale. This is the chalky deposit that typically collects around faucets and areas that come into frequent contact with water.
Limestone can be difficult to scrub off, but spoiled milk can help. Simply apply the liquid to affected areas and let it soak for several minutes. The lactic acid should breakdown the deposits so you can scrub them away. Follow up with a cleaning spray to remove the scent.