Art is objective, there is no such thing as good art or bad art. Art is whatever inspires or provokes an emotional response from the audience.
In the issue/debate surrounding good art versus bad art there are some measurables by which critics may deem art as either good or bad. Good art is communicated clearly and sincerely, also it should focus on one emotion: to do otherwise would confuse the audience with mixed emotions. Other distinguishing features that may be applied to "art" in the debate is that it should have: 1. Appeal: that it should hold beauty for the viewer; 2. Timeless: beyond fads or fashion; 3. Endurance: should reward contemplation, repetition and continued absorption; 4. Message: art containing a message, has added complexity and allows it's audience to engage with it on multiple levels.
To summarize, art should be viewed objectively, and a good critic, while the art may not appeal to them, should be able to appreciate the concept and emotional message being portrayed by the artist.
"Bad painting, good Art."
"Weeping Woman" Picasso
Museum of Modern Art, Vienna