Well, let's start saying that if someone calls your piece "a piece of shit" that person should be ignored. It is important as well to apply filters to what other people say about your work.

I am not talking about negative comments, I am talking about "this feels something is wrong here, maybe it could go better if you do this and that". But definitively if someone comes and says "hey this piece of crap of yours is a loss of time" then clearly that person is just trying to play funny by judging you and being a total jerk.

Once again, you gotta filter these critiques and use them in your advantage, if you listen to everything that everybody say and not even translating the message, then you are in trouble.