Surely calling music bad isn't even a case of subjectivity anymore? Some music is just plain sh
ite. For example, my brother is currently listening to a song called "Feeling Myself" by Will.I.Am and the ever-so-classy Miley Cyrus. It is sh
it.
Evidence:
'Cause we be in the club
Bottles on deck
And God dammit, God dammit
I'm feeling myself
'Cause Imma get it all
And Imma throw it up
Like God dammit, God dammit
I'm feeling myself
God dammit you the sh*t
You the sh*t, you the sh*t
God dammit you the sh*t
God dammit you the sh*t
You the sh*t, you the sh*t
She give me IQ, that mean she get a head
I just give the beats, I don't give a bread
From another song by Little Wayne.
Real Gs move in silence like lasagne.

Well, AH, I think it's fair to say - You are the sh
it. 
Got anymore terrible examples?