As for whether it is good for the host, it depends on personal beliefs and concepts. For those who believe in Feng Shui and folk traditions, hanging red flags can bring good luck and protect family safety. For others, this may be considered as an outdated practice or unrealistic.
In short, hanging the red flag is a manifestation of cultural traditions and personal beliefs, and there is no scientific basis to prove that it has practical effects, so whether it is good for the owner needs to be judged according to personal circumstances and concepts.