as Ighalo said, they do exist. But then again, as social psychologist, I believe individual's personal value (inc. worldview, etc) plays bigger role in their topic of choice and their research paradigm. For example, some are more positive toward social phenomena, while others are negative. Regarding the outcome, I do think some traits can influence it, e.g predisposition to dishonesty can make a researcher justifies that falsifying data is okay or so; or laziness results ghost writing. I've seen such things happened, and honestly, it is way more common than we think. But then again, my observation might be biased and too negativistic.

Yes. For example, Duarte et al (2015) criticize that psychologists, especially social psychologists, are quite left-leaning which can bias the research findings: "This lack of political diversity can undermine the validity of social psychological science via mechanisms such as the embedding of liberal values into research questions and methods, steering researchers away from important but politically unpalatable research topics, and producing conclusions that mischaracterize liberals and conservatives alike." https://www.cambridge.org/core/journals/behavioral-and-brain-sciences/article/political-diversity-will-improve-social-psychological-science-1/A54AD4878AED1AFC8BA6AF54A890149F

As a result, conservatives were long characterized as more biased by social psychologists, but a recent meta-analysis argued that both left- and right-wingers are equally biased (note that this meta-analysis has been criticized as biased itself)Article At Least Bias Is Bipartisan: A Meta-Analytic Comparison of P...