Ok, good post! I agree in the sense that other people can help you grown as a writer (of any kind). The problem, however, remains that the OP asks what are 'good' lyrics. You can say good lyrics are lyrics that are proven to be populair. It was a populair believe that the earth was flat a few centuries ago. Does that mean that that was good? We have discoverd that that was in fact bad. With lyrics this kind of total rejection of ideas will not be able to happen probebly, but when Beethoven premiered his Grand Fuque a lot of people left the room. They where saying that his harmonic language was not good. This was a populair believe. Does this mean his harmonic language was indeed bad? It was a leap forward and it is now considerd populair believe that is was, indeed, a leap forward.
IN the baroque erea fourths between two voices was considerd bad, because they felt is was to harsh, to dissonant. That was a populair believe. We believe now that a clash of a c major with a an c minor chord is dissonant. Whil people still think about it that way 100 years from now? Tritones where considerd devlilish. This isn't a populair believe anymore.
The same goes for lyrics. Populairity/ what others think might display the populair believe at this moment, but it will most likely change. If you always test your lyrics/music/art to the populair believes you will sty within that circle. That's a deathcentence for creativity. If you look at the most populair artists from the last 80 years. Where these considerd populair by the time they started out? Or did they develop somthing that has grown populair.
Galileo was convinced the earth revolved around the sun in stead of the other way around in spite of what almost everybody else was saying around that time. Who's point of view is more populair now?
I agree that you can learn from what others tell you about your art. But you should not try to listen to them in terms of good and bad. You are the only one who can dicide what is good and what is bad. First of all, because it's all relative and subjective. Second of all because populairity is by no mean a token of what's good and what's not.
It is kind of a responsibilty to try and find out for yourself what's good and what's not. If you make the wrong decision you might never earn something with your art. And it's true that aiming for a populair market is one way to earn money.
But if that is what the OP wants to know, then he asked the wrong question.