Bulls are trained before the fight
Bulls enter the ring completely untested. Indeed, to train them or acquaint them with the movements of the matador would be counterproductive and very dangerous to the bullfighters as bulls do pick up on the visual ruse played on them after a while.
As a bullfight progresses, while the bull grows physically weaker, it develops a sense of the person behind the cape. A bull which has previously been submitted to passes with a capote or a muleta will develop this sense far earlier. A knowledgeable crowd and professionals will immediately detect the difference in the bull’s behaviour and demand a replacement animal.