Typical scenario at work.
Client, "Stuck injector? That can't be what's wrong with it. Are you sure it's not the spark plugs like I thought? I was pretty certain that's the why it was running rough when I dropped it off for you to look at."
Me in response, "Well, I did show you what I'd found inside your motor, and what I feel will repair the problem. Furthermore, I had the spark plugs out, inspected them and they appeared fine. Diagnostics show you're getting signal and power to them. I replaced them anyway for good measure because you requested that and it didn't help your situation." :)
Me internally, "IF YOU KNOW WHAT THE MOTHEsmurfING PROBLEM IS, WHY ARE YOU TAKING THE CAR TO A GARAGE?!?!? IF IT WAS JUST SPARK PLUGS YOU WOULD HAVE DONE IT YOURSELF!! LISTEN TO ME, YOU $&%!@& MORON." :mad2: