Can you judge a book by its cover?

I read Darfur: The Ambiguous Genocide, by Gerard Prunier, and was quite impressed.  I thought "what a smart and unbiased introduction to such a difficult topic."  But why was I impressed?  I don’t know nearly enough about the topic to judge the material.

I was impressed because the author sounded so reasonable and so intelligent.  But I can’t cite any really good reason to believe this was more than a trick.  Prunier sure didn’t seem as if he were trying to talk me into a hidden agenda.

Bryan Caplan offers his heuristics for trusting a source or not; here’s Arnold Kling on the same.  Here’s David Henderson’s podcast on disagreement.

I tend to trust sources who use their intelligence to point out flaws in their own positions.  But is this more than an aesthetic preference on my part?  What’s so trustworthy about that?  Maybe I’m just looking for people who remind me of myself, and what’s so good about me anyway?

If my trust standard works, it is only because not so many people use it.  If more readers trusted on the basis of "using intelligence to publicly question one’s foundations," that standard might be too easily to manipulate.

In other words, it is the stupidity of much of the audience (they can be fooled by simple tricks, complex tricks are not needed) which makes it possible for the more sophisticated readers to read signs of intellectual dishonesty and get closer to the truth.

Let’s say you have a medium — call it a blog — which is read only by very smart people.  Simple, relatively discernible tricks won’t be used.  Should those readers then have a special distrust of the authors?