There are many examples here, both positive and negative, but I keep wondering, why people anonymize the unfavourable ones? I'd really love to know which company was that "company X", "company [HNer] won't publicly name", or "well known company in these circles". Those are important data points in order to know whether or not one should get involved with a particular company.
Because often they're very anecdotal. Companies like Google employ hundreds of recruiters. It stands to reason that out of those hundreds there are a few who are not particularly great (downright bad, even). I also hear that big names make people sign NDA's when interviewing, although this has never happened to me.
Additionally, naming and shaming often isn't very beneficial for your career! People move around a lot, especially in recruitment.
I suspect that people don't want to leave a traceable record of themselves badmouthing companies for doing nasty things. Ceasing to consider another party after hearing what they did to someone else goes both ways.