A few days ago, Nobel-prize winning biologist James Watson made some pretty racist comments (which he has since tried to retract). Watson is one of the co-discoverers of the structure of DNA, and deserves the accolades he's received for that achievement. But his remarks are inexcusable and non-scientific.
Like any human, we scientists are full of our own biases and opinions. When we are working on our science, we must set those biases aside (as much as is possible), but I've never met any scientists who have been able to rid themselves of biases and opinions. It's part of being human, and it's also a driving force behind the advancement of science. If we didn't hold opinions, fight for them, and feel driven to search for evidence supporting our ideas (or against someone else's ideas), then science would go nowhere.
Often, too, as scientists succeed and become secure in our jobs, we tend to explore a little more of the fringes of science. I've seen physicists exploring ESP, an astronomer who thinks he's discovered evidence of extraterrestrial civilizations, and other such things. I think it is okay to explores such issues if one feels like they can shed new light on a topic, but typically the evidence is no stronger than supposition and tying together facts that don't really mesh. As one friend once said to me, "There's a little bit of crackpot in each of us."
None of this excuses Watson's remarks, and hopefully outbursts like his can show that racism continues to linger in places where many would claim it has been abolished. However, it is important to stress that his remarks are those of Watson, the human, not Watson, the Nobel-winning scientist.