Reliability rating

We should create a news outlet / blog rating system
minus one point every time they make a post/story which reports as fact an incident that is not true (without stating that the story is in doubt)
In the case of the MAO book people like NoRightTurn, Daily Kos and so forh would seem to have lost a point.
Plus one point every time they argue against somthing that turns out to not be true.
I am not sure where to place reporting the story with a disclaimer that it may not be true - this might deserve a point also.