Meme-ish

Meme-ish Traits
The following traits tend to cause ideas to propagate out of proportion to their value as ideas:
 * appeal: some ideas are appealing, regardless of their truthfulness, and thus are more likely to be adopted by individuals encountering them
 * comprehensibility: ideas which are easy to understand ("this medicine will make you healthy" as opposed to "if this medicine makes you feel worse, that's good because it confirms diagnosis A, which we can treat...")
 * explainability: ideas which are easy to explain or convey (people will often swallow sound-bite explanations without taking the time to really understand them)
 * juicyness: some ideas make good gossip, or good headlines, or otherwise appeal to the motives of those with the ability to rapidly spread them (e.g. dirty political campaigning often spreads "truths" well known to be false, and leaves them in the popular mind for many years).
 * practical untestability of claims: if a claim isn't easy to prove or disprove, this makes it harder to argue against the meme (because it might be true); this is particularly effective when combined with promise / threat
 * promise / threat: ideas which promise reward and/or an avoidance of some undesirable consequence ("believe in the Word and be saved; those who believe not shall go to Hell" or "you need to wear make-up or men will think you are unattractive" or "you really need these ultrasonic deer sirens on your car if you want to avoid an accident")
 * repetition, i.e. meme spam: ideas which are deliberately seeded repeatedly tend to spread more rapidly; because of such spread, any given individual will tend to encounter such ideas from multiple sources, thus lending them additional credibility.
 * self-spreading: ideas which encourage the recipient to spread the idea ("send this email to 10 of your friends"; "spread the Gospel so that others may be saved")

In general, these traits are most effective when combined in particular ways that effectively put up roadblocks against any of the obvious "exit reasoning" strategies, and thus make the meme very difficult for each new victim to resist.

Quotes
In support of the idea that memes can be "fine-tuned" in different ways, regardless of their accuracy or value, so as to be appealing to various groups of people (who might not otherwise agree with each other or with the meme), and then "hammered in" (repetition) to create a significant voting bloc whose opinion on a particular issue is known to the manipulator (and perhaps unexpected by all opponents):

The potential for manipulating mass opinions and feelings initially discovered by commercial advertisers is now being even more aggressively exploited by a new generation of media Machiavellis. The combination of ever more sophisticated public opinion sampling techniques and the increasing use of powerful computers to parse and subdivide the American people according to "psychographic" categories that identify their susceptibility to individually tailored appeals has further magnified the power of propagandistic electronic messaging that has created a harsh new reality for the functioning of our democracy.

(Is this a new discipline -- memetic targeting?)