Liars. The CBO was corrupted and intimidated by the thug-in-chief right after their first scoring of the health care bill. Remember the private meeting between Obama and Elmendorf in the Oval Office in the early days of the health care bill?
As I understand it the CBO can only do thier analysis based upon the numbers that Congress give to them and Congress only uses the numbers that look good for them. It is just like a computer if you put garbage in then you get garbage out. The CBO I believe tries but it is limited by Congress.