As you suggest, not all charities are benign. Some are for funding terrorists, others for purely monetary gain, and still others for nursery of left-wing nuts.
http://www.freerepublic.com/focus/f-news/2151886/posts?page=38#38
Here are the lists of the left wing groups Madoff nailed. They continue on down the page, and are not just limited to this one post.