Basically we look at your total submission history and as stated above check to see if it's copy-pasted content, or custom made content. Once we see a trend of these submissions you are promoted to verified composer. Unfortunately i have been busy away from the sites lately so i have not been able to check the queue submissions myself. And the SSR's seem to have forgotten to notify me if they recommend someone for the rank...
But we have fixed this problem via staff chat, so they will be more on the look out now.
Further Edit - It has nothing to do with whether i like the songs personally, just has to do with the quality of the submissions and making sure its not spammy or of very poor quality as well.