Life is better with colors.

Originally, haint blue was thought by the Gullah to ward haints, or ghosts, away from the home. The tactic was intended either to mimic the appearance of the sky, tricking the ghost into passing through, or to mimic the appearance of water, which ghosts traditionally could not cross.

It’s also good for keeping wasps from building nests for the same reason

(Or after reading the wiki, maybe an indirect one relating to the use of lye in the paint)

Haint blue is a collection of pale shades of blue-green that are traditionally used to paint porch ceilings in the Southern United States.[1][2]