2 of 7 edited this answer a bit, this will probably the post we link to in the future

The Wikipedia community relies on the No Original Research core policy to combat unsubstantiated claims from finding their way into articles:

Nutshell http://upload.wikimedia.org/wikipedia/commons/c/ce/Nutshell.png This page in a nutshell: Wikipedia does not publish original thought: all material in Wikipedia must be attributable to a reliable, published source. Articles may not contain any new analysis or synthesis of published material that serves to advance a position not clearly advanced by the sources.

The very purpose of this site as defined by the FAQ contains nearly exactly the same idea (my emphasis):

Skeptics - Stack Exchange is for skeptics, rationalists, free thinkers, or anyone who questions pseudoscience. Skeptics is about applying skepticism — it's for researching the evidence behind the claims you hear or read.

The voting system of Stack Exchange is largely meant to relax any need for specific policy regarding what constitutes a valid answer (and by and large it accomplishes this) — however, due to the nature of Skeptics, the community (and perhaps the FAQ) ought to promote the idea of no original research to encourage healthy voting.

Bad:

  • "...since I have personally experienced it numerous times"
  • "Anecdotally, I've seen it..."
  • "I heard that it was also caused by ..."
  • "I'm not sure if this idea comes from some research"

Good:

  • "There is a fairly comprehensive article on the topic at..."
  • Even better, multiple sources
  • No citations, but a thoughtful experiment