Myth: Switching shampoos can make hair look healthier.
Truth: It may seem so, but experts scoff. "Hair can't tell the difference between brands or build up tolerance to any product," says London-based hair and scalp expert Philip Kingsley. "Your favorite shampoo will work the same every time you lather up, week after week, month after month." If you have very oily hair or favor a particularly sticky styling product that contains wax, it does pay to use a clarifying shampoo once every two weeks to wash away residue.