Here are some common arguments for the "no poo" method, and my counter arguments.
"My hair is so shiny" - Really? Maybe that's because it's so greasy.
"My hair holds any style" - You know how wire stays when you bend it? This.
"I don't have to wash my hair as often" - I guess this just depends on how greasy you like your hair to look.
"I just have to blow dry my hair and go" - When it wasn't weird and greasy, my hair went strange and frizzy and stiff (both at once! weird!) and I had to use my straightener to make it look any kind of normal.
Also, this made my head really itchy and gave me dandruff. It was as though I had a buildup of dry bi-carb on my head, even though I washed it out very thoroughly. Now with real shampoo, my hair feels silky rather than stiff, clean rather than coated in grease, shiny rather than frizzy, and my head doesn't itch. I would like to reduce how much I shampoo, though. That will be my next experiment.
Here is a link to someone else who failed at no-poo. She has a more in-depth discussion which is really interesting.
No-poo, I am disappointed in you. Disappointed.