In his very interesting book, Garlic Cloves & Red Underwear, Joseph L. Cacibauda not only describes the many ways the Italians of the past followed to protect themselves from the evil eye and harmful influences, but he also explains why some objects are considered bearer of good luck and others of bad omen.
Actually, even today, people buy charms. They believe that these objects bring them good luck and ward off evil influences.
When we went on a trip to Naples, I saw quite a few street vendors selling red horns and other amulets. One of our friends bought a small bracelet made of small red horns and gave it to us. She said that, to be effective, the amulet must be given as a gift, not purchased.
We accepted the amulet. We still keep it with us, although we are not superstitious. You never know!
Overall, Garlic Gloves & Red Underwear is an instructive and easy to read book. I recommend it!