The decision what is good art and what is not is a decision indivdiuals and/or groups within society take. Those indivdiuals/groups might not necessarily be in total overlap with each other. You might e.g. have particular sub-groups who enjoy noise music, something the majority of people wouldn't even call music. That sub group might consider a overwhelming fraction of popular music bad music. Similar a particular country fan might consider rap and techno not music at all, or bad music while they like their own thing very much.

Sometimes (often?) these critiques contain an element of social or cultural connotation as well. Techno definitly is hedonistic, rap and hiphop are connected to certain demographics and classes within society, as where the Beatles. That means a criticism should always also be seen in that light: Who criticizes whom from what standpoint? If that country fan dislikes the latest and harshest noise rock release that might be a good guide for fellow country music afficionados, but someone who likes noise rock might rather take that negative review as a compliment. Both sides could try to use the border they draw towards the other as cultural capital within their own ingroups.

That means when the Beatles became popular a lot of the criticism they got was also criticism the old generations had towards the younger generations. It was not only about the music, it was also about who decides what good music is.

Today (thankfully) we live in times where objectively good art is revealed as the delussional idea it always was.