Which conspiracy theories have merit? Which are nonsense?

By what criteria do we determine which conspiracy theories have merit and which are nonsense? That question -- the underlying theme of many previous Cannonfire posts -- seems more germane than ever, now that we've seen the rise (and fall?) of Sandy Hook "trutherism." In fact, that question forms the basis for a couple of interviews I've conducted behind the scenes, the results of which you will soon see.

Right now, I'd like to share a follow-up communication with one of those interview subjects. Here's the message I sent him earlier today:

Last night, I watched an episode of Jesse Ventura's "Conspiracy Theory" -- the one about water. Ventura decried the fact that bottled drinking water in the U.S. is unregulated: "They could be putting ANYTHING in there!"

But in the same program, the former governor relied on Alex Jones, a self-identified Libertarian. The whole point of Libertarianism is to get rid of regulations and to trust the corporations.

Isn't there a massive contradiction here?

I decided a while back that one way of judging the potential worth of a conspiracy theory is to ferret out the political stance of the person offering it. If you have a theory to sell to me, don't expect an easy time of it unless you share my anti-Libertarian, pro-FDR economic viewpoint.

What do you think of the notion of using ideology as a quick-n-dirty way to assess the possible worth of any given parapolitical idea? Such a criterion may seem unfair at first blush -- but for me, it works.

Let's be honest: No-one can claim total freedom from bias. Any conspiracy theory originating with an admirer of Ron Paul, Ayn Rand or Milton Friedman will probably repulse me. (As you know, the Paulies are notorious CT junkies.) I might yet be turned around in favor of said theory, but only if the weight of the evidence exceeds that of the key to Superman's Fortress of Solitude.

What are your criteria (and biases)?