I remember one of my professors back at University said: If someone irritates you, they have a power over you. The worst thing you can do when you have received a negative comment is to be defensive because it only gives more power to offender. So, the question is how to react on negative comments? From my own experience, I think there are two main options.
Firstly, you can ask why the person think so, and what would they improve? The key is to focus on the facts, concentrate on the issue not the person. They might have a really good arguments, and you can actually learn and improve something. Try to turn negativity into constructive feedback and constructive discussion. But if their arguments are really general without proven points and overall shifting towards being rude and insulting, I would thank them for their opinion and forget about them.
The idea is to treat everyone with the same level of respect but that doesn’t mean you have to agree with a everyone’s opinion. The last thing you want to do is to let someone you don’t even know to drop your confidence level down. Pick you battles😉 and stay positive 🙂