I have always been very skeptical of preachers and doctrines. In fact, I will not read a book or listen to a preacher/teacher, unless recommended by a close friend, one that I know I share many theological viewpoints with, or this person has spoken at my church, or my pastor mentions this person. I have just seen too many flaky things in church.
Of course, we all need to be checking the Word to see if what we're being taught is truth. I have actually spent the last five years questioning doctrines I was taught, growing up in church, to see if there is scripture to base them on. Many of them I have found verses for. Basically I am at the point that I don't want to teach my children anything that I can't show them scripture for.
Deception is rapidly increasing in so many areas of our world. I am almost done reading Religion Saves and Nine Other Misconceptions by Mark Driscoll (at the recommendation of my pastor). I was introduced to this idea of the emergent church (I guess I am in a bit of a bubble) and I was floored! These people call themselves evangelicals, yet are so polluting the gospel. The leaders of this movement are Brian McLaren, Doug Pagitt, and Rob Bell, among others. They have large followings, their books are even for sale at ChristianBook.com.
It's got to the point that you don't know if someone says they are a Christian, if they hold to the same Christianity that you do. All the more reason to focus on Matthew 6:33 (see my top banner). We must be diligent in our study of the Word (the only absolute truth) to do just what Jesus told His disciples, take heed that no one deceives us.