Just to add a bit of Danish levity:
I arrived in BLL one night and the loaders refused to work until I shut the APU down (I wanted to stay warm during a 20 minute turnaround).
"Why" said I?
"It makes too much noise and it says so in our rules"
So, I shut the APU down and switched on the Brake Fans (which made more noise than the APU).
That blew the whole union plan apart because there was nothing in their bits and pieces that mentioned Brake Fans and I pointed out that this was a matter of flight safety.
I think I won the moral high ground that night.