The list is long...
-Working with people that is not passionate about what they do. So far in more than 20 years in the industry I've never been in a kitchen where everybody shares the same passion for cooking and do things to the best levels based only on the great feeling that only getting things perfect gives. Most of them cook because they get paid to do so, and try their best because otherwise the chef is going to pound on them, but if there were no supervision they'll do things on a sloppy/dirty/careless way.
-Vegans, vegetarians and "sauce on the siders".
-Requests from friends who have "A friend, son, relative, acquaintance" that "wants to be a chef" and is studying , and asking you to give them the chance of training in your kitchen... And the worst part, when they get offended by the negative from yours truly.
-Lawsuits from cooks that you helped big time over the years.
-The huge drug consumption by the people in the industry... If I make an antidoping test I'm sure that I'll get 80% positive from my staff.
-Opinionated people that is not even in the industry and wants to share his "wisdom" with you, in front of his guests.
-Last minute customers that take 20 minutes looking at the menu and then asking for a 4 courses dinner and one of them being a well done 2.5 Lb meat cut.
-Anybody asking for a premium meat cut cooked to well done.
-Being the guy that has to solve it ALL.
-Getting aplications from "cooks" that call themselves "A" class cooks that don't even know how to make a properly made clear and rich stock.
-The dreaded "Chef...Can I talk to you?" line from any of my good cooks... Usually nothing good comes from that.
-Seeing "Cooks" cutting with dull knives turning beautiful scallions or herbs into a mushy mess. When I see that they know that I'm sending them to "Washing-town" (They become dishwashers for a day, 3 days or even a week).
-Salespeople that wants to talk to me in the rush hour...Usually those guys get the worst from me...But somebody has to teach them that service hours are not the best to talk to chefs.
-Equipment getting broken on a Friday or saturday night. Why not monday morning?... Murphy's at his best!
-Know it all "cooks" just coming out from culinary school... Those ones that on the third day of working start a discussion with me on how cool some of my dishes may get if we "de-construct" them. Those ones get the "Washing-town" treatment too...That will teach them to focus on hard work specially at the beginning of their careers wich is more important than going "de-constructing" my hard to construct and popular dishes.
And I can keep with hundreds of nuissances that make my day difficult or annoying... But maybe I'm a bit of a sado-maso guy because I'm still doing this and loving it. Who knows?