My favorite was when they would claim the radio stopped working right after I replaced their vinyl top.
It was often enough that I would have to tell my guys to never touch the radio. If it’s on or off, leave it that way...and don’t change stations or volume. If you touch the radio, you are fired.
Too many of the guys would hop in the car to move it into the shop and immediately turn the radio on and tune it to their favorite station so they could hear 10 seconds of music. Then the customer would claim it was on a different station and try to use that as the reason their radio failed.
I just got tired of the stupid fight with the dumbass customer who was just looking to get one over.