I think that in general the approach that the main wikipedia site takes is a good one - I've been called on several changes I made where it turned out I couldn't verify the facts, and one where I was plain wrong. I've never had a legitimate entry or change reversed, with the exception of one site link (to the only on-line edition of a long out of print book) which turned out to be selectively quoting from it to make a political point - I'd put in the reference without realising that large and important parts had been cut.
