I think the best answer anyone can give is that there is no good answer.  To say that the current Presidential administration has anything to do with it is a little off to me -- I don't really think that the Bush administration gives a damn about DC.  The sting operations are being carried out by DC police, not by the Justice Department.  Ashcroft might have something to do with it, being the tightwad that he is, but somehow I doubt it.  He has bigger fish to fry right now, like answering to Congress for telling Bush it was ok to torture people.  I think Ockham's Razor might come into play here: the simplest answer is the oversaturation one that you provided.  It's gotten too out in the open for the comfort of the law enforcement officials and/or the community at large.  Other than that, I'm not sure there is a good answer.