A negative comment is only really negative if no one learns from it.
People will always be more likely to point out what you are doing wrong than what you are doing right. It is human nature to seek the errors in others.
For some this is because they truly feel they are being helpful by pointing out your flaws and they may well be. In these cases, the individual will be approachable, but often hard to convince from their opinion – right or wrong.
For a few, it is because they actually do know better than you do and are trying to educate you. These are usually very polite and open to constructive discussion.
Sadly, for many it is because they lack the courage to put their opinions out their themselves and feel that it is necessary to belittle those that do. These are usually anonymous one liners.
Either way, negative comments can lead to a positive outcome for you, if you are prepared to accept that there is that slight possibility you were wrong or made a mistake.
However, as I said, a negative comment is only really negative if no one learns from it, even those little one liners may have value.
Face to face is one thing. People are much less likely to be outright negative and rude. However, online it is much easier for people to make comments that are just plain pointless. Left to make the individual feel superior in some way. These are usually anonymous, have no constructive worth and serve no real purpose.
Anonymity makes people very brave, but sadly does not make them more intelligent.
In those cases there is nothing to be learnt other than where the delete button is.