Quick cable swaps may or may not be why double blind testing has varying results.
That quick snap judgement call of a power cord's performance usually changes over time.
What you may not hear/or like could change as the cable settles in with the system.
Disturbing cables in my system after cleaning the connectors periodically, could make you believe that cleaning cables with Deoxit can do more harm than good.
After a few hours, things settle back in and you realize it was worth the wait.
It takes a bit of time to evaluate how any thing new is performing in a system.
I realize someone will chime in and say that it's just me getting used to the new sound, so I'll do it now and save them the trouble.
What is important is if I enjoy the new sound or I don't.
I wouldn't get used to a drop in performance,but I can state that I have gotten used to an increase in performance, and when that bug bites, you keeping looking for more.
That's why I have replaced all the stock power cords in my set up with ones that have made the music more enjoyable to listen to.
I wouldn't be enjoying my music as much if I had stopped at one power cord upgrade.