When I say objectivity, I'm not talking about a lack of emotional attachment. I like to see a little emotion in an article. What I'm talking about is the preconceptions, axes to grind, political stances that most people bring to their studies. You're going to have anti-sex crusaders, pro-sex crusaders, those seeking to end child trafficking (I'm not saying these are bad stances, ok?), Men's Rights Activists, psychologists who take the point that all sex workers have been abused in their childhood, people who believe that sexuality is binary not a spectrum--people who set out to prove a conclusion without letting their data lead them.
I myself have to be careful of this. If the vision I have for my character is A, J, and W, I can't let myself get bent out of shape if my research says it's more likely that while he may be J, it's unlikely that he's W, and the chance for an A is right out. I can't massage my data.