Okay this isn't about headphones but it involves non audiophiles.
Well, I was once budget speaker shopping to replace my cheapass tinny congested weak and harsh portable speakers. So when i wanted to test some sets with my own source, i asked him to to turn down the bass knob. He turned it up. I told him again to lower it. He maxed it out. "nevermind-" I interrupted him, and turned it down to neutral.
The second day, i went to another shop to test more speakers. So before i started i asked where the bass knob is situated. (because i know it would be turned up) so the shopkeeper pointed it out to me but at the same time turned it up even higher. It was annoying because everything became a boomy muddy mess so i immediately turned it down. At the end of the day all the demo speakers had their bass settings at neutral. Talk about community service.