All very true. There are some exceptions although quite slight. I find that dissertation students and first year PhD students tend not to be invested in the outcome, and they are probably the few truly open minded investigators, although this is largely because they don’t know the background to the research, but have an inherent, what I would call cognitive or intellectual, interest in an area. They are, however, guided by a supervisor, who is likely to select the methodology.
Looked down on by a lot of scientists is exploratory research although, again, they may have a personal interest which biases them, but they could just be interested in a topic out of curiosity.
Paranormal psychology is one area that suffers from this. Experimenters who are skeptics find no effect but believers do.
I think there is a thingy in physics which says that as soon as you start observing something you change what you observe