Can any scientist really be objective?

I think Stableboy wrapped it up, but they are still subject to the same financial pressures as everyone else, like who pays their research budget.

They may then be swayed by that factor, but i'd hope not.

The collective practice of science is reasonably objective: having your results reproduced by other scientists tends to flush out personal biases. So the main biases that are left are those which are common to all humans, because all scientists are humans.

An example (I think the prime example) of such a bias is the presumption that there's some solid underlying basis for objective reality. It sounds absurd to challenge something so basic, and yet the more science analyzes and fragments reality in its search for the ultimate basis, the more it seems to slip through our hands: e.g. substances become molecules, molecules become atoms, atoms become particles, particles become subparticles, and subparticles start having such an ethereal existence that we can't even say what it means for them to "exist".

And yet, scientists are just like the rest of us: we presume that there's some "solid" foundation for what we call reality, when in actuality all that can be found is infinite flux and change, all relative.

I think it really depends on the question -- not your question -- but the question the scientist is evaluating. You can say anything you want with statistics -- so stableboy's answer about peer review tends to make scientists play fair.

There is also the concept of the "double blind test" -- where neither the control group or the evaluator knows who is in the control group. But that only prevents a scientist from aiming for a test result... it does not prevent the scientist from not revealing the test result.

We learned from the tobacco industry that known scientific test results can be hidden in favor of test results that say what the scientists want them to say. Consequently, I don't trust scientists any more than any other religious zealot.

Sure they can, and many are.

We owe a lot to science.
A good scientist is also a good person.

To be truly objective, they need to be honest, dedicated and leave any personal bias or personal agenda behind.

Don't forget about the pharmaceutical industry. They conduct "ethical" research, but only show the results that serve their financial gain. They present studies with marginal clinical benefit but "statistical significance" that browbeat doctors to use their products. Ambulance chasing lawyers are chewing at the bit to win the lottery with a patient who suffered from statistically "proven" inferior medicine.

Today's western scientists presume that they are objective because they validate their observations with their physical five senses. Ultimate reality of the universe is not limited to the physical assumptions of our culture.