SHAME ON TYLER PERRY and Oprah Winfrey for signing on as air-quote executive producers of Precious. After this post-hip-hop freak show wowed Sundance last January, it now slouches toward Oscar ratification thanks to its powerful friends.Winfrey and Perry had no hand in the actual production of Precious, yet the movie must have touched some sore spot in their demagogue psyches. They’ve piggybacked their reps as black success stories hoping to camouflage Precious’ con job—even though it’s more scandalous than their own upliftment trade.