Have you ever considered...
... that McGruder's comics are poking as much fun at (what you predictably call) the leftist stance as they might be at black conservatives? My local paper carries "Boondocks", and that's how I've been reading the recent series of finding dates for Condee Rice, etc.
In a twist of synchronicity, the movie Pleasantville just ended (TBS had it on this morning). Lighten up, Tom... the world isn't black-and-white, even in the daily comics.