In any contentious science/policy issue it's easy to find people on both sides who resort to ad homs and poor arguments. Using that as a metric to judge any one sides' credibility is a fallacy.in response to Ted Nordhaus:
In the face of scientific complexities that are difficult to parse, one easy heuristic as to where credibility lies is to what degree partisans resort to ad hominem, misrepresentation of opponents arguments, and sweeping, unqualified assertions.People often want some simple heuristic to know who to trust, which side is right, in cases where they can't be bothered, or aren't capable, of working out the truth for themselves. To be more accurate, people often search around for a simple heuristic that allows them to choose the side they already know they want to choose, and ignore the inconvenient opinions and facts from the other side.
This is covered in Scott Adams is a tosser.