I read books on all sides, by all kinds, whats left out of some, and spun by some makes history the only true determinant of what policies work.
Liberals are the best thing that happened to Palin, she was a focus for them to see how disinterested the leadership of the Republican party was in broadening their appeal, and how conciliatory they were to the fringe of their party. It didn't work, and now wiser heads are distancing themselves from the far right element, even as those in the far right make more noise. But the leadership will not be giving money to the fringe people in the next election, they don't want more losses.
Many of those books are being bought by right wing churches and organizations for resale, and reading a book, doesn't imply approval of policy. People really aren't indoctrinated as simply as a book or a song. Unless they have a very low level of critical thinking.