In a previous life, working as a red cap in CPH, I did run into the occasional chip-on-the-shoulder skipper who thought he was god. Always a he, and nearly always from one of the countries bordering the Med. Either that or Lufthansa.
First trick is to tell him, ever so politely of course, to !!!! off and let you do your job. If he refuses, then leave the flight and tell your manager that due to whatever reason (safety always a winner) you are unable to complete your assignment. Second trick is to file your complaint before he gets a chance, just to cover your backside. I've only had to do that once, walking away and writing up a report that is, due to an absolute pr1ck of a TAP skipper. I won't dwell too much on details, but he got on everyone's nerves from loading over fuelling to catering, pax service and weight & balance - treating all staff as if they were incompetent children. His CRM skills were somewhere between naught and f.all. He almost got lamped by a particularly big hairy scandihoovian belly rat who really didn't fancy being d1cked around by this self-proclaimed skygod. I actually had to interfere; had I not been there the skipper would have been down for the 10 count right quick.
As luck would have it, 99.9% of all crew are nice and professional to work with, and I'm sure the same can be said of dispatchers. It's the odd .5% that tend to ruin things, and I can tell you 1000 stories about kind, professional, helpful, cheerful crew who more often than not made my day for every bad story I have.
Never had the misfortune to work for a real despot of a boss. If it was to happen, I'd rather walk away than be miserable about going to work everyday. Better to flop burgers for a nice boss than dispatch aeroplanes for a certifiable w@nker!