I just had a thought I've never had before. As you all know, some people believe in a thing called the placebo effect, which is (when the term is used outside of a medical context) when someone imagines grand differences in quality between product A and product B due to product B having a much higher price tag than product A and due to oratorical prowess on behalf of the marketing team behind product B when, in fact, there is a negligible or even nonexistent difference between the two competitors. I must confess, I too am a believer in the sneaky little bastard who goes by the name of Placebo.
However, what if, and this is just a thought, what if those of us who are determined not to let our brain influence what we hear are nevertheless letting our brains effect what we hear just the same as victims of the placebo effect do? What if we don't hear differences between gear or downplay them because we're trying to be so vigilant against the snares of Placebo? What are your thoughts?
I think what you are describing is called confirmation bias. This this is just as real as the placebo effect.
If you make yourself a blind-test and believe there's no chance to pass it, that means you already have a hypothesis and you will search/recall for information that reinforces the hypothesis.
A possible workaround would be to make a double-blind test. Someone else prepares a blind test for you in a way you don't know what's going to be tested (so you don't know whether you "should" hear a difference or not). After that you will be the one who runs the test (without any preconceptions) and the test subject. That way, confirmation bias is eliminated. At least that's what I think.