Unlucky is a very personal thing. What I would consider an unlucky colour would be lucky for someone else. Cultures and circumstances differ widely.
As an example: Where I was raised both black and green are incredibly unlucky colours to wear to a wedding, and very nearly disastrous if worn by a member of the wedding party.
It is not considered bad luck.
It is not considered to be bad luck to wear a Claddagh if you are not Irish. In fact it is considered good luck.
In some cultures, cutting nails on Friday is considered bad luck.
A jinx.
No, black is not considered a bad luck color in dogs.
In some cultures, it is believed to be bad luck to point at an eagle.
Wu Mei was considered bad luck by her family because her mother died while giving birth to her. They told her that she "caused her mother's death" and that she must be bad luck.
I am not sure if there is a symbol but the colour red is considered to be a massive sign of luck. x
It is considered bad luck because it wastes nourishment for the whole family.
butterflies and moths
Number 13.
In Indian culture, seeing an owl is generally considered as a sign of bad luck or a harbinger of death.