Without specific examples its always hard to tell what is going on. Sometimes I have found that people who are foreign from those being commented on, may sound harsh, when its simply a language difference. Sometimes a person can have a strong overbearing personality and they are just that way, not realizing how harsh they come across. Other times they are nothing more than ignorant trolls. For myself, I tend to engage people who seem like trolls in friendly private chats. I've actually ended up friendly with many a person who seemed angry or aggressive initially. And they are usually good people behind the nasty mask. Miscommunication is very common. Some people lack the social ability to put forth critique in a nice way. But outright trolling should be reported. There is no excuse for it.
My advice. If not sure about a comment's true meaning, ask for clarification. Put the commenter back in the hot seat and have them explain more how their advice can help them.