Stories from the NIS, formerly the KCIA, usually turn out to be true. The "feeding his uncle to dogs" thing was from a Hong Kong tabloid, which is generally a mouthpiece for Beijing and does get some things right, but was certainly not an appropriate source to go to print with. The girlfriend execution story was from the Chosun Ilbo citing unnamed sources in China.

The unicorn story was actually reported on by KCNA and published internally. Now, whether or not North Koreans actually believe state media stories of unicorns is another matter, but the fact remains that state media frequently publishes outlandish tales regarding the leaders and stories that seek to promote the idea that the DPRK is a special or magical place.

The thing with the DPRK is, there's the state media, which borders on useless for gaining any information, and there are spy/defector networks. That's all you have for information from the north. It's a near perfect information vacuum. NKNews is pretty well connected to various defector groups and people within North Korea who keep cell-phones, but even their sources cannot freely travel throughout the country and rely heavily on rumors that slowly spread by word of mouth through the country.

The NIS, despite being some really nasty bastards when it comes to South Korean politics and abuse of the citizens of South Korea, has a big budget and runs a very effective spy network within the DPRK. As far as stories on North Korea go, the satellite imagery combined with NIS verification of the story puts this in the 95th percentile of North Korea news.