Likewise, if commenter A on some blog calls a view "a conspiracy theory", commenter B is going to show up and point out that calling something a conspiracy theory is not a strong argument as conspiracies actually exist and then C (or A) is going to say that the term "conspiracy theory" is meant to highlight the unlikeliness of an explanation not because it refers to a conspiracy per se, but because the kind of conspiracy A was referring to would require a large group of people to share knowledge about their conspiracy while keeping outsiders in the dark about what they're doing.
I would think that latter argument is a good one (although if it weren't I wouldn't know, as I don't know about the things I'm being kept in the dark about). We should hence be skeptical if someone offers a conspiracy theory in C's sense. For example, we should be skeptical about Robin Hanson's view that teachers use the educational means of homework not because they believe it to be an effacacious means of learning or because making people do stuff is fun, but because politicians, educators and businesses are colluding to produce another batch of serfs for businesses big and small by means of schooling, all the while leading the public to believe that education is actually about taking in knowledge. (Hanson would never put it in those terms, which would preclude him from falling back on the position - which comes in handy when dissenters present arguments - that his argument is merely that the discipline learned by pupils in school is an outcome of school, an observation bordering on the trivial. Also, one wonders whether spelling out the argument in its full Marxian glory might harm carreer prospects in George Mason University's staunchly libertarian econ departement, where Hanson is employed. But that's his argument nonetheless.) It seems rather unlikely that the hundreds of thousands of people who would have to be involved in that conspiracy would be able to keep the secret for any extended period of time.
Hanson describes himself as having "a passion, a sacred quest, to understand everything, and to save the world" (bold type his), but perhaps it's more accurate to say that his passion for finding The Real Truth behind well-known patterns is as Freudian as his grandiosity.
As is the accuracy of his explanations in some cases. So why is this kind of writing so popular among people who aim to be much more enlightened than the average Joe? I believe it was Jean Paul who came up with the idea that the success of Freudianism came about because it gave people what they wanted: sex and crime. Likewise, you could say that Hanson's idea about the aim of education has potential because people like stories about powerful people conspiring against us little people (and most disliked school).
I think there's a heuristic in there. All other things equal, people are going to dislike boring explanations in favour of those that are interesting. When encountering an explanation, ask yourself whether a film containing the same ingredients could have a shot at becoming a blockbuster. If the answer is yes, discount a theory's popularity as an indicator of its being correct. You can also use this principle when trying to devise a popular theory. Make sure it goes boooom and whoooosh a lot!