I had a similar situation. I got a call from the Job Supe, telling me the code rail was loose and I did a bad job. I got there and checked it out, he basically started yelling and screaming about quality, yada, yada, yada. I started looking at it and started to pull drywall screws out of the brackets that were screwed in to the drywall only, etc. I asked him who were the last ones in the home and he said the painters were. Then I told him to go look in my truck to see if he could find a single black drywall screw in the entire thing. Finally it clicked for him and he did apologize.