I never knew what all the hype was about clarifying/purifying shampoo. Shampoo is supposed to clean your hair so what could this stuff do any differently? I finally caved and gave it a try after trying a hair mask that was way too heavy for my hair and left it in a 
weird, crunchy, wet look. I went to a beauty supply store and they suggested trying a clarifying shampoo. I made sure to get one that was for color treated hair because I was afraid it would strip my color. I gave it a try and WOW what a pleasant surprise! My hair was shiny, softer and way more manageable. Additionally, my products seemed to work better than they previously had.
There are a variety of clarifying shampoos to try; the one I went with was by Halo. It was $19, but you are only supposed to use it once a week, although I think I will go with once every other week since my hair is so fine. I imagine this one bottle should last me about a year.
So in a nutshell: believe the hype about clarifying/purifying shampoos. They get rid of product buildup in ways normal shampoos can’t. The results are amazing!