....but hard to imagine that factor alone can explain those claims.
Yes, it certainly is. But then a couple of suggestions. Experimenters have discovered that when the same item, be it an audio component, food item, or most anything else in consumer land, and presented it over and over under blind conditions, same item, absolutely nothing changing, people still identify differences, at a rather high rate. How come?
We are wired, the brain is, to look for differences and the brain has a hard time when it is asked to decide if there is a difference, it picks one instead of saying no difference.
Why do listeners pick one brand of speakers in sighted tests and the other one under bias controlled testing? Toole has shown this as probably has others.
As an anecdote from the past by another poster who did a sighted, single blind experiment on his family with salsa, I believe. Two plates with salsa, two different bottles in front of the plates, or rather behind it. Asked th efamily which tasted better. Certainly they picked one over the other. They were the same salsa on the two plates.