Why are the top surfaces of some public places painted black?

The store opened before was also painted black. My reason is: there is no money to decorate, and the ceiling will cost a lot of money, but there are many water pipes and the like on it, which is ugly without cover. All the decorators say that painting black is good, and the effect is good, and no dirt can be seen. Black painting in public places should also save taxpayers money. Dirt-resistant and economical, it should have no special meaning ~