When I use this shampoo, I know my hair is clean and healthy. Back in the 80's while in school for Cosmetology, the instructor warned us the students to never use Prell. There was a commercial where they showed Prell shampoo in the bottle and dropped a pearl in it to show how thick Prell was. The instructor said the reason we never saw the pearl reach the bottom was because it dissolved due to the acid in Prell. I had used Prell along with other shampoos all my life and my hair never dissolved, so I knew she was full of it. I noticed trying to find Prell in my normal stores was becoming impossible and up until about a year ago, I went onto other shampoos. When I saw 1 bottle of Prell in my store I grabbed it and was thrilled, its gone now and again no more Prell has surfaced in my stores of choice. I love the simplicity of how they stayed true to their product, oily hair uses more shampoo, 2 washes, dry hair less shampoo, you don't have the problems given when you try to match your hair with 10 different types of the same shampoo. Prell also works with any conditioner, don't rack your brain on that. I just wish it was obtainable w/o online and delivery being involved, too much of a hassle.