The media is the number one problem. Eager to come up with a story, they will be very selective in what they choose to report. Goldacre sees the link between MMR and autism as essentially a media hoax, for which there was never any substantial evidence. He also investigates more closely some of the 'experts' produced by the media, and finds that often their academic qualifications are not what they seem. Conventional medicine might seem to blind you with science, and to be influenced too much by big pharma, but this book shows that alternative medicine is also fond of 'sciencey' language (usually without any substance behind it) and is also often surprisingly profitable.
There's a worry, though, that if you try hard enough then it's possible to debunk anything. Goldacre seems to dismiss a 35% increase in cocaine use in schools much too easily. Mostly, though, the book does it's job very well, teaching you how to spot the media's misinformation in a readable and entertaining way.