Well. Those sites and three Attorneys General and the GAO (looking at just the ACORN findings).
Regardless of that fact, because he printed/made an untrue video in the past doesn't mean that what he is presently doing is the same. People tend to lean toward absolutes, but truth is a sliding scale where various media outlets produce varying degrees of misinformation.
Certain things are not valid arguments:
1) Fallacy fallacy - Presuming because something was poorly argued (or presented) and therefore is wrong.
2) Genetic fallacy - Presuming someone's argument is invalid based on who it is from.
3) Tu quoque - Turning criticisms back on the person raising them, evading their points.
These are the type of arguments I see liberal-minded folks use all of the time on others, and everyone single one of them is a complete logical fallacy.
Points are distinct and unique, and someone being wrong about one thing doesn't indicate whether they are currently wrong. They could have made mistakes, or found more information "this time", etc. Anyway, I think anyone could see my point from here - each assertion needs to be compared individually and analyzed or you are bound to get into trouble.