From James Ladyman in Understanding Philosophy of Science:
Kuhn’s history of various scientific revolutions shows us that individual scientists do not live up to the philosopher’s ideal of maximally rational agents, always making decisions based on the evidence independently of their own personal interests and goals. On the contrary, according to Kuhn, scientists are often very much attached to a paradigm, and sometimes particular individuals will do almost anything to retain it in the face of contradictory evidence, including perhaps, distorting experimental data, using institutional power to stifle dissent, using poor reasoning and bad arguments to defend the status quo, and so on. Indeed, sometimes the established scientists will refuse to adopt the new paradigm and, rather than being persuaded by rational argument, eventually they simply die out, while the next generation get on with developing the new approach. Of course, disreputable behaviour and fallacious reasoning seem to be features of all spheres of human life, so it would be pretty surprising if they were never found in science, and clearly the idea that all scientists are saint-like pursuers of the truth is unrealistic to the point of being ridiculous.