@roger,
A good fact checker gives their sources. Facts are based on evidence.
When Trump says that Hillary started the birther controversy there is video and written evidence from the time. When Trump says that millions of illegal aliens who are voting, there are voting records.
Facts are facts and you easily see from primary sources when they are factual. You do not have to trust the fact checkers. You can check their work.
That is why it is so frustrating that Trump voters are basing an argument on obvious untruths.