a climatologist or claims to work in this is discredited by association.  Other examples of reasons why scientists can't be trusted are when a group of them in a certain disciplines such as archeology or anthropology insist what they know is absolute. Examples would be the Clovis first theory in America. Regardless of all the evidence that exists demonstrating humans were in fact here before Clovis as well as multiple Asian and European contact during this time are all dismissed. By nature these disciplines can't make definitive claims on any part of the past because the information available is limited, incomplete and not necessarily interpreted correctly. This does not mean every reasonable theory or accepted truth should be discarded every time a new theory appears but when evidence exists to the contrary of a theory it should be investigated.  Scientists who have maintained their reputations and credibility probably do not get as much scrutiny as the scientists in fields where it is very obvious bias is there. The bias might be their own beliefs and pet theories, getting grant money, advancing their own reputations but the end result is questioning their integrity.  Had today's scientists performed actual science where we can confidently assume the experiments were done with the expectation of obtaining results that prove or disprove a theory, then their credibility would not be questioned so much. Another problem not mentioned really is politicians. When it is politicians who declare CO2 a pollutant with the backing of grant purchased