"You need lather to know it's really working."
Myth

The more foam a shampoo produces, the cleaner your hair's getting, right? Not exactly. You may love working up a good head on your head, but those suds are mostly created for psychological effect (Oooh, it's cleaning!). Foaming occurs when surfactant molecules in the shampoo mix with air and create millions of tiny bubbles. "Ideally, your head should have only enough lather to lubricate the hair and scalp, so a 50-cent-sized blob of shampoo will usually do the trick," says Steven Hanna of Christopher Hanna Hair in Sydney.

"You should use a clarifying formula to get rid of build-up."
Partly fact

Unless you're using heavy-duty styling products, like pomade, mousse or gel, regular shampooing prevents styling-product residue from collecting on your hair. If you do need a clarifier, don't use it more than once a week. "These detergent-heavy cleansers, which do such a great job of removing build-up, will also do a great job of damaging the hair cuticle," says Hanna.

"Washing every day can be bad for your hair."
Mostly myth

"Daily washing is safe and healthy," says cosmetic chemist Westman. If you have oily hair, it's fine to suds up every day - but even oily types should use a gentle formula (translation: one with moisturising ingredients like silicones, shea butter or panthenol). People with coarse or dry hair might want to be more conservative and wash every other day, says L'Oréal's Youssef. No matter what kind of hair you have, as long as you stay away from harsh formulas that strip natural oils and treat your strands with conditioner, regular shampooing won't do any harm.

"For best results, follow with a conditioner."
Fact

No, this isn't a scam to sell you two products. Chemists can pack only so many ingredients into each bottle. And a shampoo can't clean properly and deposit enough conditioner to moisturise your locks. "Using a separate conditioner will coat strands with ingredients that hydrate and protect," says Hanna. BTW: if your hair's super-oily, apply the thick stuff only from the ears to the ends.

"After a while, your hair gets used to your shampoo. That's why you need to switch to a new brand occasionally."
Myth
Honestly, where do people come up with this stuff? Let Westman set the record straight: "Hair is dead, full stop. So it can't 'get used to' anything. It's just your perception of how your hair responds to a new formula." So if you love your brand, there's no reason to switch.