I am a firm believer in Sturgeon's Law:
90% of everything is crap
Some folks see Sturgeon's Law as somewhat negative.
I, OTOH, am the optimist & look on the brighter side. No matter how worthless, vile, talentless, or just plain banal some thing or some genre is, 10% may actually be something better than crap. It might rise to the level of, "mildly interesting" or even, "not something for which I would hunt down the perpetrator and beat with a 2x4 for stealing that 3 minutes, 45 second of my life."
So far, I must rely on my faith in Sturgeon's Law with regard to rap, as I have yet to hear anything that is not...crap.