Why the need to：
In Taoism, believer believe if there is deity, there will be evil spirit, “dirty spirit”.
Before moving into a resale property, believers believe that a chanting to send off evil spirit is necessary as to have a peace of mind.
Some believe that premises that are vacant for long period of time are considered to be a safe haven for evil spirit. Hence, the evil spirit may occupy the premises.
Generally, believers believe that if a person is down on their luck（时运低）, they are easily possessed by evil spirit or being followed them back to their home. If there is no deity in this family, the evil spirit will stay in the house, and may bring trouble to the person or the family.
These are the 3 common scenarios that believers most often hear or encounter.
In order to get rid of the evil spirit, believers will engage a Taoist priest to conduct ritual to ask them to leave.