The idea is that results and conclusions cannot be bought by the sponsor but the researcher must be free.
Example: you profe that medication X is benifitinal for a low blood pressure.
Sponsor: You state, that your study has been paid by company X which is interested in producing and marketing medication X.
Problem: company X has bougth research that is good for their product and marketing... All in all this is innaccaptable for good ethical research, and in particular for the researcher that is doing such bought research...
It can indicate a conflict of interest. Some researchers might follow the research rather than personal or monetary interests (even so, they should still openly list where the funding to conduct the research comes from). The proper way to do this is to disclose ones leanings and interests. Past experience or field of expertise can also indicate the method which a researcher will go about to find answers. Whomever one associates with, determines the norm from which that individual operates from. Unconscious biases might also arise from the environment.