Bulls Hate Red Color and Charge When They See One.
Bulls Get Angry when they See Red color.
Hoax or Fact:
An angry, snorting Bull Charging at a Matador’s (bullfighter) Red color Cape/Muleta is a common scene seen in Bullfighting. There's also this common belief among people in general that Bulls hate red color and they get wild and charge when they see one. So we have always been told not to stand in front of a bull when wearing a red colored dress. But as a matter of fact, the popular claim is a Myth, because Bulls are actually Color Blind to Red.
Bulls, like other Cattle, are actually color-blind to red. Not by red color, the Bulls are most likely irritated by the Cape/Muleta’s movement as the matador/bullfighter flutters it around. In 2007, the Discovery Channel’s program MythBusters tested a live bull on color versus movement in three separate experiments using Red, Blue and White flags. They came to the same conclusion; the Bull gets irritated not by the red color, but by the fluttering movement of the cape/muleta. Bulls will charge at any object moving the most. It should also be noted that the Bulls used in bullfights come from very aggressive breeds and they are raised in such a way that any sudden movements of the cape/muleta will make them angry, leading to the attack.
So even if the cape/muleta were of any other color than red, the bull will charge at it as the bullfighter flutters the object around. Spanish matadors have been using the red color capes since the early 18th century, because they are seen as part of the traditional bullfighting uniform. And in most cases, the red Muleta is only used in the last stage when the Bull is killed by the matador; the red color cloth of the muleta helps mask the sight of the bull's blood.