In its original sense, a shaggy dog story is an extremely long-winded anecdote characterized by extensive narration of typically irrelevant incidents and terminated by an anticlimax or a pointless punchline.
Shaggy dog stories play upon the audience's preconceptions of joke-telling. The audience listens to the story with certain expectations, which are either simply not met or met in some entirely unexpected manner. A lengthy shaggy dog story derives its humour from the fact that the joke-teller held the attention of the listeners for a long time ... for no reason at all, as the end resolution is essentially meaningless. [Wikipedia]From The Washington Post, August 20, 2015:
The day after a devastating take-down of the Iran deal from Sen. Bob Menendez (D-N.J.), the Associated Press reports:
Iran, in an unusual arrangement, will be allowed to use its own experts to inspect a site [Parchin] it allegedly used to develop nuclear arms; this under a secret agreement with the U.N. agency that normally carries out such work, according to a document seen by The Associated Press.
The inspection regime and dispute resolution system was already riddled with loopholes that Iran will exploit. But with this there is not even the pretense that there is a viable inspection process. With self-inspection comes the open door for Iran to cheat with impunity. The AP report continues:
The Parchin deal is a separate, side agreement worked out between the IAEA and Iran. The United States and the five other world powers that signed the Iran nuclear deal were not party to this agreement but were briefed on it by the IAEA and endorsed it as part of the larger package.
Without divulging its contents, the Obama administration has described the document as nothing more than a routine technical arrangement between Iran and the U.N.’s International Atomic Energy Agency on the particulars of inspecting the site.
[...]Reportedly the average Shaggy Dog story takes about five minutes to tell but there are numerous instances of a story dragging on for an hour or more. In fact the funniest part of a Shaggy Dog story is seeing how long the teller can hold the hearer's attention to a completely ridiculous tale.
However, the Obama Iran Deal Shaggy Dog story might make into the record books -- although it could be that the Obama presidency will top even that record.
Unless you want to turn it around and say Barack Obama is the best Shaggy Dog story teller to ever speak into a microphone. But from that viewpoint, the punchlines have always been at the expense of the American press and public.
Now as to how a Shaggy Dog story came to be called a Shaggy Dog story, there's a story about that....