It was a Lush bar that started me off looking for an SLS free shampoo, because it made my scalp so unbelievably dry and itchy. I finally realised I was reacting to something rather than assuming I just had rubbish skin and hair. Lush shampoo bars contain a higher proportion of SLS than liquid shampoo. All their shampoo contains SLS, plus a lot of their conditioners, including the supposed 'co-wash' bar.
If they work for you, that's great! But if your hair and skin react badly, I strongly recommend trying an SLS free shampoo. I spent years struggling with my frizzy hair, flaky scalp and dry, irritated, red skin, assuming I was just unlucky, and trying various anti-dandruff shampoos that made things worse not better. Now that I don't use products containing SLS or silicone, I have glossy hair and clear, bright skin.
I'm delighted to find that there are companies making SLS free shampoo and conditioner bars, and have my eye on a few products from the Funky Soap company. I'd prefer to cut down on plastic if I can.
I've nothing against Lush as such, and regularly buy some of their skincare products, but considering they are a brand that caters for sensitive skin in other products, I really wish they'd offer an SLS free shampoo and conditioner bar.