Young Brunette Girl Reveals In Black Stockings At The Wall With A Mirror

There is a Buddhist belief that negative spirits will enter houses that have a triangular-shaped roofs through the door. Hanging a small circular mirror in front of the door will prevent the bad spirits from entering.
In days past, it was customary in the southern United States to cover the mirrors in a house where the wake of a deceased person was being held. It was believed that the person's soul would become trapped in a mirror left uncovered. This practice is still followed in other countries (e.g., Romania), extending to everything that could reflect the deceased person's face (such as TVs and appliances). Another explanation given is that the devil will appear in the reflection of the dead. Mirrors falling from walls or otherwise breaking or cracking mysteriously were said to be haunted. A similar custom existed in Greece, in the belief that use of mirrors is a sign of vanity that does not become mourning. (Other Greek mourning customs include not playing music, not entertaining guests, and using no festive decorations, e.g. on Christmas, during the customary year-long mourning period).
According to legend, a vampire has no reflection in mirrors because it is an undead creature and has already lost its soul.
Another superstition claims it is bad luck to have two mirrors facing each other.