Oh no, there is no agreement to this statement above. Not in Philosophy. Not in Theology. Not in Science (there is a science to beauty though symmetry/asymmetry). Not in music (harmony). And yes, not in Literature. Yes, there is bad poetry. And no, good poetry does not only mean Shakespearean rhymes and couplets. Some of the best emerging poems are in hip hop, which include social commentary on inequality and vulgarity - and yes, hip hop artists are not necessarily advertised as paragons of virtue… but I agree with some posters that to be truly great, a poem should stand on its own, even independent from the non-literary characteristics of the author.