How rare is it to get a male calico cat?

Not very rare. There are quite a few around.

Albinism is a rare genetic condition existing in all plant and animal life. For every physical characteristic that a living creature displays, there are two genes. Some of these genes are dominate while the others are recessive, or "hidden" Albinos are simply born without pigments in their flesh.

Not all white animals are albino, and there is no such thing as part-albinos. If an animal has coloration or dark eyes, they are only white, not albino, a true albino will have either red eyes, or a very translucent blue with a faded appearing iris, depending on the species of animal.

In order for the albino recessive gene to be able to make an albino individual, the parents of that offspring must both have at least been carrying that recessive gene, or were fully albino, thus only capable of passing on the albino gene. In any case, wild animals born albino tend to die because they do not blend in with their surroundings. But domestic animals may show up albino more often due to humans selectively breeding them for the trait. They are not always blind as goes common theory, however, an albino animal will battle a larger scope of health problems, which may include blindness, deafness, and immune efficiencies.

At any rate, an albino, because they have no pigment in their tissues, sun burn easily, and often go blind from sun exposure, and have a higher rate for cancer. Thus, despite how mysterious and exotic albino animals are, they should not breed with other albinos so as to prolong the gene, because the deficiencies will only get worse with subsequent generations. This is why we had our albino dog neutered. The deaf albino tigers in the zoo that cause people to suspect all albinos are deaf are a result of inbreeding, and prolonging the albino trait which resulted in the deaf gene to affect all albino tigers in captivity, it was due to limited breeding stock to desperately attempt to save a species, not a characteristic of albinos in general.