Amazon calculates a product’s star ratings using a machine learned model instead of a raw data average. The machine learned model takes into account factors including: the age of a review, helpfulness votes by customers and whether the reviews are from verified purchases.
It works for me. I colored my hair from dark brown to blond and it turned out brassy and orange in the roots. It’s not fully gone but it is way better than before. I leave the shampoo In for 5-10 minutes. It really dries the hair so you need a good hydrating conditioner afterwards. Can recommend!