You have to understand, it is not that they necessarily believe what they are saying.
The point is, they will take anything that casts their side in a negative light and might be perceived as a positive for the other side, and they will do whatever is necessary to diminish it by deflecting the claims, confusing the issue, lying, and repeating the lies, and drawing attention to unrelated events that cast the other side in a negative light.
This is page after page of exactly that.
I dare say, even Unkle Carmine slime of the earth is not as stupid as appears here.
The hope is to minimize the political advantage the other side might otherwise garner, and to perhaps catch a few of the completely ignorant and uninformed among their base who don't have the intellect or attention span to follow (and arrive at the truthful conclusion).
What is lost is an adherence to the truth and any sense of fairness. Democratic principles of an informed electorate are what is lost.