I often find myself fascinated by the two-faced way in which most, perhaps even all, people approach those things that they agree and disagree with. In my experience, it's very common to see someone criticize, rightly, a particular flaw in the thinking of one person, and then appear to be blissfully unaware that the exact same criticism can be made of their position.
Probably one of the most common places that one sees this is in politics. It is common to hear the left deride, with good reason, the right's tendency to court people opposed to actual science on religious or political grounds (evolution denial or global-warming denial, anyone?), and yet endorse the equally anti-science ramblings of many left-wing folks (for example, a large range of questionable claims about "natural" medicine come from the left*) - and please note that I am using the terms "left" and "right" as they are used in current U.S. political discourse, I personally don't think that we can simply cut politics into two halves like this but that's a different blog post.
Likewise, it's common to hear Republicans ranting about the "lack of rationality" and "over emotionalism" of the Democrats, while concurrently using scare tactics, nationalism, and claims that "if X happens, then the terrorists have won!" to prevent their own members from actually stopping to think about matters.
I recall a commenter on one of my blog posts about Proposition 8 claiming that if gay marriage was made legal by vote, then this would be the "tyranny of the masses" forcing those opposed to gay marriage to accept it as a legal reality, but this same person was apparently unaware that they were supporting the same sort of "tyranny of the masses" to control the personal lives of other people.
Living in Santa Cruz, probably the most common place that I see this is when I hear a proponent of an untested medical therapy state that "medical establishment" is opposed to the therapy because "big pharma" (which is often used interchangeably with "the medical establishment") is driven by the profit margin and therefore would rather keep you dependent on drugs to treat the symptoms than to actually heal you. However, the companies producing herbs, vitamin supplements, homeopathic pills, etc. are also businesses which profit (to the tune of $34 billion per year) from consumers buying products**. In other words, the alternative health industry has the exact same profit motive that the major pharmaceutical companies have!
And as I type this, I can think of the many, many times that people have patiently (and sometimes not-so-patiently) shown me that I have engaged in this very same type of fallacious thinking on various pet issues of mine. I am grateful (if somewhat embarrassed) when people point this out to me, and I know perfectly well that I am unaware (or hiding from myself) of other issues on which I am guilty of this.
That's the thing, all of us are guilty of this, it's a common human trait. Skilled politicians and marketers can cause us to fall into it, certainly, but our own worst enemies are ourselves. We all hold positions that are incorrect, and that we would realize are incorrect if we were able (or allowed ourselves) to view our positions and especially our rhetoric and reasoning as an outsider would, and yet we are masters at fooling ourselves and rationalizing our own positions. Some people do this more than others, but we are all guilty.
So, what is to be done? I don't know. Certainly, pointing it out when you see it may be useful, though most people have built up enough layers of rationalization that this is unlikely to have much of an effect. Accepting that you do it, and trying to be open to criticism when others point it out will help. Still, I don't know that this is something that can be eradicated even within oneself.
*There is, however, one major difference. While such claims absolutely exist on the left, the left has not organized as well as the right, and therefore you don't see concerted efforts to, for example, force medical schools to teach homeopathy int he same way that you see pressure to put creationism into science classes. So, there is a difference, but it's a difference of application, not of type of thinking.
**A particularly high-profile matter at the moment is that one of the things that the anti-vaccination groups claim is that "big pharma" wants to keep putting out vaccines and "pro-vaccine propaganda", while the anti-vaccination folks peddle a long-debunked anti-vaccine report by Andrew Wakefield that was produced fraudulently in order to help Wakefield's own business dealings! In other words, the whole anti-vaccine hysteria was sparked by someone who falsified data to make money from payments from attorneys suing a vaccine producer and also his own work to produced a competing vaccine.