We both have some sparse short, fine hair on our tails (click either of the photos below to see all the details). This is typical of Sphynx. The CFA Breed Standard states:
COAT/SKIN: the appearance of this cat is one of hairlessness. Short, fine hair may be present on the feet, outer edges of the ears, the tail, and the scrotum. The bridge of the nose should be normally coated.
We are both registered with TICA, and this is what the TICA Sphynx Breed standard states:
The Sphynx appears to be a hairless cat, although it is not truly hairless. The skin should have the texture of chamois. It may be covered with very fine down which is almost imperceptible to both the eye and the touch. On the ears, muzzle, tail, feet and scrotum, short, fine hair is allowed. Lack of coat makes the cat quite warm to touch. Whiskers and eyebrows may be present, either whole or broken, or may be totally absent. The cat should not be small or dainty. Males may be up to 25 percent larger so long as proper proportions are maintained. The Sphynx is sweet-tempered, lively, intelligent and above all amenable to handling.