One problem with dry shampoos is that although they do remove a lot of the gunk from your mane, they don't get the hair quite as clean as wet shampooing [source: BeautyBrains]. The latter not only causes the oil to form droplets and slide off but also causes chemical changes in the oil-secreting process that slow down the mechanical spread of oil from your scalp to your hair shafts [source: Zviak]. "If your hair is really dirty," says beauty author Edain McCoy, "It may take so much dry shampoo to make it appear clean that you take away its natural shine, or cause it to look like your white, powdered head just popped out of the 18th century" [source: McCoy].
Nevertheless, the popularity of dry shampoos seems to be rising again. Recently, avant-garde hair care experts have resurrected a notion popular in generations past -- that daily shampooing does too much damage to the hair. They're championing the idea of going several days to a week -- or even longer -- between wet shampoos and using a dry shampoo in between. There are even some adherents who are giving up the wet stuff completely, in favor of the powder [source: Grossman].
Even if you like your regular wet shampoo, hair stylist Robert Vetica recommends dry shampoos for women with fine, easily damaged hair. Even if you use wet shampoo, he suggests using an aerosol dry shampoo as a rejuvenating touchup for your hairdo if you're planning to go out after a long day at work. "Your hair starts to lose its style as the day goes on," he writes. "Take the dry shampoo and give your head a good once-over, leave it for a few minutes to let it absorb all the oils from the day, and then give it a good brush through" [source: Vetica].
One potential drawback of dry shampoos is that the top designer labels, which retail on the Web for as much as $24 for a 3.2 ounce container, can be pricey, though less elegant brands are available for a fraction of that. Beauty expert McCoy suggests a cheaper DIY alternative: Cornstarch brush a small portion through your hair, being careful to rub it in around the roots [source: McCoy].