I don't when I go to their comment section and see that they have other types of comments, I see that there's a real person behind the screen. But if I see that it's only "Nice post" over and over again, every 20 seconds - then usually I flag.
In 99% cases I try to explain first why it's not the way to go, but most of them become rude that very moment.
Thank you so much for your attention o my blog, I really appreciate it:)