String theory. Or rather the ethos that string theory is the only answer and that it is necessarily right. Smolin feels that the tactics employed by string theorists to keep other ideas out of the field (e.g. not inviting proponents of competing ideas to string conferences) are unethical and hurting physics. He dislikes the fact that so much of the available funding is going exclusively to string theorists, when string theory has failed to produce testable predictions for so long.
I'm just paraphrasing, I may have gotten details wrong. I haven't read the book, but I've read a couple reviews.
There is a review of this book, and Peter Woit's Not Even Wrong in this month's SciAm.
On the topic of Motl, Peter Woit claims that Motl offered readers of his blog $20 for any successful one-star reviews of Woit's book on amazon. That seems pretty unethical and downright nasty to me.