Yes, some folks are riding the "fad train" and profiting handsomely from the current popularity. That is true no matter whether it is a diet, a sports team, or a TV show that is currently en vogue. However, there are quite a few people who are actually focused on the science and evidence behind human nutrition and health.
The best book I've come across that dives into the research and nearly every important epidemiological study in the last 200-300 years is Good Calories, Bad Calories by Gary Taubes (http://amzn.to/149HYzi). It's not exactly an airplane read and certainly not a "diet" book; however, it completely changed the way I think about nutrition, exercise, disease, and overall health.
I would also recommend anything by Loren Cordain or Robb Wolf.
Before you make any judgments, do the research.