However you do need to be prepared for those who have a negative approach. They take upon themselves a self appointed cause. According to them they are the official cleaners of the internet. They seek to share with you the negativity. They could get a little too intrusive in the way they comment. They could be doing it with honest intention of sharing valuable thought processes. They tend to bring to your notice on what is wrong or the other side of what you have written. They have the self appointed mandate to draw yours and other person's attention to the fault in what you may write. They like to be the typical devil's advocate. They share another point of view.
Many a times they may be right. It is good to have them on board so that you have a check on what you share via your writing.
However, many a times when you track them and read their comments you would start to see that they are a little out of context. You may get the feel that they are on a rampant to share negative conversation. The reason they may do this could be various. They could have met an unfortunate past experience or they could be on a sad trip of life in their current situation. Reasons could be ample after all they too are humans. They perhaps could have not understood what you may have written and perhaps could have interpreted in a wrong way.
You need to respect their comments, step back and think if you would really want to entertain such comments. You need not lose your temperament. You can flag them as spam, you could delete, or choose to ignore. Your answering them is not a bad idea either, just that it will lead to an inane conversation of ego clashes.
You could track them and see that many a times they prove to be having a monologue. No one really comments back to them. They ofcourse feel they are in the right and what they are doing is a correct method and way to go about things. While they have a point to prove it is entirely your choice on how you want to reply.