If there were one simple thing that could vastly improve most "political" art it is that idea of expressing a universal critique, applicable across history as well as to current events, without ever having to say so. That in and of itself is not enough to make it good art, but at least it will work toward preventing it from being disposable. To make good art, I think Joao indicates the right approach as well: "resonant, uneasy, and incisive" (with a huge ol' emphasis on incisive). I haven't had the pleasure of seeing this exhibition yet, so I'll take Joao's word for it that it does this, but as the article indicates, one measure for whether politicized work is good art, or merely an illustration of a talking point, is "Does it ask more questions than it tries to answer?" Any political art with more answers than questions is suspect, IMHO.
Edward references the work of Adam McEwen, whose work is showing at Nicole Klagsbrun in New York. I think that in order to understand the reviewer's comments, you would have to see the show. The images provided on the gallery site don't really seem pertinent.