I'm sure there's some genuine friendships, but it's always interesting to see what people say publicly vs. privately. Also fair to say that there are people I've worked with that I did not, at the time, appreciate but grew to appreciate later on.

Years ago I was at an event talking to a colleague who was absolutely bashing someone (with good reason) and then another colleague walked up. Same person came up and my first colleague changed tone to "yeah, so-and-so is an interesting character."

Because I knew that the other colleague also hated the person, I called him on it. I wonder, though, how often that dynamic plays out where nobody will voice a negative opinion publicly - so people slide by without being called on behavior that shouldn't get ignored.