I keep my hair very clean, but it's visibly oily by the second day after a wash and I'd really like to be able to go three or four days. (If that sounds unkempt, try growing your hair out sometime! Washing too frequently is more than inconvenient, it accelerates wear and damage)

Can anybody suggest a mass-market dry shampoo that will remove oils without depositing too much powdery stuff that makes it dirtier the next day? Or do I just towel it off with rubbing alcohol instead—it seems to work!