The thing I like about Ben Goldacre's book is that it is equally ruthless on both "mainstream" and "alternative" medicine. If you got your holy grail, cure-in-a-bottle from a doctor who got it from a Pharma rep or if you got it from a website, it doesn't matter. You still have to be able and willing to do the investigating yourself and find out if the "science" behind it holds water. There are examples of both good and bad science on both sides.