The Answer is =>>>   For those who don't understand, this is a trick that many housekeepers use to ensure cleaner clothes in difficult conditions. 
Because use the method of soaking clothes in hot water to deodorize or wash them cleaner, especially when staying in a boarding house, where sanitary conditions may not be guaranteed or the water may not be clean. Soaking clothes in hot water helps kill bacteria, deodorize and clean clothes more effectively, especially when there are no good washing conditions like at home.