Why do scientists try to eliminate bias in their experiments?

Sometimes, even when scientists try their hardest, they miss important things that should have or could have been controlled in their experiments. After all, anyone conducting research of any kind will have to start with a set of assumptions about the observations being studied. But it is not always clear that researchers in a given field are sharing the same set of initial assumptions. If scientists don't even make an effort to be clear and objective, and let biases affect their thinking, then conflicts and problems multiply. From a radical point of view, it is probably ok for scientists to be as completely biased as they want to be, provided that they are breathtakingly and completely honest in how they report the construction, controls, results and biases that went into the research. Being biased is absolutely NOT the same thing as being dishonest or deliberately mis-leading. Blatantly mis-reporting or mis-representing data and analysis is NEVER ok, although it does occur from time to time.