From the above linked article:
we have no way of knowing the biases of the fact checkers at Snopes – we simply have to trust
Disagree. Bias in this case is mostly irrelevant, and likewise trust has little to do with it. Have there been times when I disagreed with their stamp of "True", "False", etc? Absolutely. But that's not really important, as the articles virtually always give the references necessary to reach your own conclusion. I lean towards conservative, but even when they insert subtle digs or irrelevant information I, really anyone with a brain can look past that. And BTW they have defended and debunked many anti conservative rumors as well.
Snopes fact checks typically do not mention contacting the authors of the articles about those events to see if those reporters claim to have additional corroborating material
Flat out false. That's pretty standard practice that I've seen in multiple articles.