I would say that all art is subjective. And I would say there are two separate questions to ask when asking if a piece of art is 'bad.' Is it 'bad' because it fails to evoke any emotion or feeling in it's audience? Or is it 'bad' because it's offensive?
Here's another one for you though - Is it bad because it fails to execute/convey its intent? I think it is slightly different than your first. I think it's possible to elicit emotions from your audience by accident, especially if you are not an experienced craftsman. But those emotions are like hitting a target you shot at in the dark. You can get something out of people if you try hard enough, but a truly good artist should be able to say, "I am going to make a sad piece," and make a piece that has that effect on people. So a) I think good art has intent behind it; and b) I think good art is able to convey that intent.