Are Rumors the Truth?

I'm going to use Archbishop Foley's insistence on the importance of truth and justice (see previous post) as the occasion to spew forth on a subject much on my mind lately. What follows is a response to this earlier post, as well as what was for me an unpleasant and slightly shocking experience last month.
Following a link to a story on a popular Catholic blog run by a well-respected Catholic apologist, I stumbled onto the blog's comments page. The story was about one of the "new movements," and most of the comments were impassioned diatribes from detractors and ex-members, interspersed with equally impassioned defenses. Comments pages are notoriously like snake pits (which is why we no longer run 'em here), so that was not what shocked me.
The shock came when one prominent head of an equally prominent Catholic apostolate also weighed in on the comments page by passing along a rumor. Not just any rumor; this person passed along --based on hearsay alone-- an accusation so vile that --if true-- the movement in question should be suppressed. Immediately & without remorse. However, since this prominent Catholic (it is SO cumbersome to keep it anonymous, but try to bear with me) collaborates fairly regularly with the movement he blithely accused, the only reasonable conclusion is that his remark was thoughtless rather than believed.
I wrote to this person. A calm letter, a semi-fan letter I would say, praising his work (which I do love), but politely calling him out on making such a malicious accusation with absolutely no evidence --and about an organization that he had reason to show some gratitude. The response was immediate. The defense was (paraphrasing), hey, it was relevant to the discussion, and information helps people to know the truth.
In the same blog, another prominent Catholic --this one a journalist and columnist for an important 2nd-tier newspaper -- also weighed in several times with his knowing denunciations of this same organization --basing his opinions not on anything he personally knows, but on the work of another journalist who states publicly that he would like to see an end to priestly celibacy, the all-male priesthood, and the prohibition on birth control and same-sex marriage.
When another reader of the blog wrote in questioning the appropriateness of the discussion, the blog-host defended the hearsay and vitriol as valid discussion in pursuit of "the truth." "This is what adults do," was the claim.
In another blog, following another link, yet another prominent writer --this one for an ecumenical Christian magazine-- weighed in with a piece of damaging hearsay. I guess I am naive, but I had been functioning under the assumption that all these people were "friends in the field," and would know better than to tear down works of the Church on hearsay alone. I assumed that serious Christians would understand better than the average bear that we are to let our "yes mean yes and our nea, nea" and not spread gossip --particularly of the most malicious kind. Reading their comments, I felt betrayed and disheartened, because there was a palpable atmosphere of sharks circling, and I'd expected better from people I admired.
Well, as St. John Chrysostom says, "Put not your faith in princes, even princes of the Church." But since the word "truth" keeps coming up in defense of remarks which are snide and malicious, it requires further examination.
That's the wind-up. The pitch will come in the next post.