I mean, it's impossible to say for sure that something is astroturfing, maybe it's just me having a particularly bad opinion of these companies, but for example

I mean, it's impossible to say for sure that something is astroturfing, maybe it's just me having a particularly bad opinion of these companies, but for example Google and Microsoft often feel that way. When you look at controversial topics with these two companies in them, you often see a whole load of negative comments and then one or two chains of comments that defend them, declare people being negative about it as being unreasonable and you generally have multiple accounts responding to each other, agreeing that this really isn't too bad. And of course, these comment chains have been voted to the top. The last part doesn't have to be a result of astroturfing, HN's voting system encourages controversial comments, as more people are able to upvote than downvote comments, but yeah, that doesn't exactly make the platform as a whole a better place.