Why should all the plaques before opening be covered with red cloth?

Before opening, the plaque should be covered with a piece of red cloth:

At first, it was to keep secrets, increase mystery or make passers-by pay more attention. Because people have the psychology of exploring mysteries, the more they don't know, the more they want to know. To get people's attention. Accumulate popularity.

Before opening a shop, the plaque should be covered. Using red cloth means expecting prosperous business and good luck.