First they do not exclude their age - this is one of the 'taboos' of our times. Second, by the use of cosmetics, plastic surgery etc. Skin, the most external tissue, thus unlike others exposed to inspection, can be viewed as a barometer of the overall well being. Sensitive to malnutrition, smoking, tiredness, age, skin, even to an untrained eye, delivers a message about the owner's condition. Modern improvements in this area include manicure, pedicure use of gloves, possibly painting of nails.
Hair seems to be an important indicator of one's sexuality and state.
Facial and bodily hair, apart from pubic and in the pits, in the case of females most likely indicate hormonal imbalance, while the growth of hair in the two other areas accompanies reproductive maturity. Unwanted hair, gets harsh treatment as an abnormality. In an experiment men were asked to sniff tissue soaked in female vaginal fluids during different stages of ovulatory cycle. The recent re-discovery of the vermonasal organ selectively sensitive to, among others, smell of skin of the opposite sex could shed a lot more light on the behavior. A new generation of 'sexually loaded' perfumes is already on sale.