"I've personally tried #11 and that stuff is really good at clarifying.I've used it after events that I got my hair styled for and it gets out all the hairspray. I've also been using it to tone down my old color(by recommendation of my stylist) ahead of my next appointment and it's helped! I follow up with a good deep conditioner. (Aussie 3-Minute Miracle is AMAZING!) I only use it like one or two times a week and any in-between washing, I use my regular shampoo and conditioner." —yourradimrad, from this roundup of best-selling products
Oh and if you're blonde but you suffer from green-tinted hair pretty much every time you get out of the pool (y'know, in the summer!) supposedly this will help take it allll out (and remove the chlorine smell from all hair colors).
Get it from Amazon for $5.14.