According to southern folklore, there is a certian light shade of blue that ghosts really hate.

All across the southern United states, you’ll find barns, doorways, shutters and even whole houses painted a light, cornflower-like shade of blue.

In the days when buildings were painted with homemade milk paint, lime was often a key ingredient. The lime not only gave the paint a soft blue hue, but according to legend, it kept bugs away as well. In time, people came to believe that blue milk paint could repel more than pests. It was said that this particular shade could keep away the unwelcome spirits of the restless dead that, from time to time, tended to get up, walk around and generally scare the holy bejesus out of the living.

Because this color kept away the ghosts (or “haints”), it came to be called... HAINT BLUE.