YCombinator seems to encourage this. Here's what they say about their dinner events: "Talks are strictly off the record to encourage candor, because the inside story of most startups is more colorful than the one presented later to the public. Because YC has been around so long and we have personal relationships with most of the speakers, they trust that what they say won’t get out and tell us a lot of medium-secret stuff."

Anecdotally, I've heard stories about Zuckerberg confessing/bragging about all sorts of nasty things at these dinners.

Really, this stuff should just be shamed. Sadly, too often calling out bad behavior just gets you called a "hater"...