When I first heard of this "dry shampoo" concept, I thought it sounded pretty gross. How does that work, exactly? I thought. In what way is spraying something on your hair CLEANING it? Like, ew! Then I tried a few and my suspicions were confirmed -- yuck and terrible!
But THEN for some reason, I gave the whole concept another shot ...
And, yes, I became a convert.
Here's the thing: you can't think of dry shampoo the same way you think of regular shampoo. It's not about really cleaning your hair; it's about extending the time between shampoos. This is great if you have a blow-out you want to preserve, or if like me, your hair looks best the day AFTER it's washed (not the same day). Or if (also like me), you are kind of lazy. Ha.
Essentially a dry shampoo just soaks up a bit of the oil on your scalp and hair. I know: sounds ick, but it's cool. For me, I can pretty much get one extra day by using a dry shampoo. If my hair is looking a little flat and limp, but not toally dirty, I can spray it with some dry shampoo (holding the can about 8 inches away from my head), brush and blow-dry it, and I'm good to go for another day (or night out!). If I time it right (so my hair isn't too far gone to start with), a nice dry shampoo really adds some volume and shine, and makes my hair really great to work with if I want to put it up. But, I will definitely have to wash my hair the next day.
As with all beauty and hair care products, not all dry shampoos are created equal, and they don't all work the same on all hair types. I think to find a good one, you've got to experiment a bit. The first several that I tried just seemed to make my hair look WORSE by adding a coating on top of my hair. But then I got a small sample of this baby: 
Oscar Blandi Pronto Dry Shampoo Invisible Spray ($11 for 1.5 oz or $25 for 5 oz at Sephora)
And I loved it! Once it ran out, I felt brave enough to tried a few others, and I really like these two:
Alterna Cleanse Extend Translucent Dry Shampoo in Mango Coconut. ($22 at Sephora) THIS SMELLS SO GOOD!
Herbal Essences Naked Dry Shampoo ($6.99 at Walgreens). This is a new product, and it's really great -- and totally affordable. I don't mind spending the money for one of the pricier bottles because I don't use dry shampoo that often, so it really lasts. But a bargain is always welcome!
Have you tried dry shampoo?