Myth 15: Applying mayonnaise to your hair will make it glossier.
Mayo is made with an oil base, and it makes hair shine. But to avoid a mess, try this method: Apply a cup of mayonnaise mixed with a teaspoon of vanilla extract (to cut the mayonnaise scent) to dry, unwashed hair. Cover your head with a warm towel to help the mayonnaise penetrate, and leave it on for 20 minutes. Before you step into the shower, apply a heaping handful of shampoo to your hair. Don't add any water yet; just massage it in thoroughly for several minutes. That will help break down the excess oil, says Berkovitz. Rinse with cool water in the shower and your hair will come out shiny and silky. If the idea of putting a condiment in your hair makes you queasy, try a rich glossing treatment, such as Phytonectar Ultra-Nourishing Oil Treatment ($30, drugstore.com), which contains egg and rich oils, the basic ingredients in mayonnaise.
Myth 16: Never pluck a gray hair, because 10 more will grow in its place.
This is false. "How can you get 10 new hair follicles from plucking one?" asks Berkovitz. If anything, ripping a hair out by its root leads to regrowth that refuses to lie flat. Your best bet for conquering gray? See a colorist.