Not sure how many of these are genuine and how many are made up, but, I just found these online, about professionals revealing a secret about their industry. SO DONT SHOOT THE MESSENGER

Sushi chef – Ahi Tuna is actually just Yellow fin tuna, it’s the lowest quality sushi grade tuna you can get.
Aerospace engineer – Every aircraft you’ve even flown in has hundreds of cracks, dents, and just plain broken parts even if it is brand new. On the plus side we do design for that. A crack can grow to three feet on a 737 between inspections before it becomes a serious problem.
Adult store employee – Many vibrators are pretty much the same item in different packaging – a company will have different “lines” of toys that are really the same toys in different boxes.
Airplane fueler - Jet fuel is not very flammable. It takes a very specific blend of fuel, air, and a spark to light it. You can drop a match in a puddle of jet fuel and it won’t catch fire.
Chef – The best things I cook are for me and my staff. They’re not on the menu.
Dock worker (building skids, handling airline baggage, handling your shipments) - Your “Fragile” stickers are useless. Your “Do Not Stack” stickers are useless. Your “This End Up” stickers, your “High Value Item” stickers, your “do not tilt” stickers, and that lock on your suitcase are all useless. They are there to give you peace of mind.
Chinese airline pilot trainers – I don’t think I’ll ever fly as a passenger on a Chinese airline in my life.
Drycleaner – Your clothes get wet in the cleaning process. The initial cost of your article of clothing has absolutely no bearing on the cost of our services.
Airport manager – Fences are there to keep wildlife out, not al Qaeda. If they want in, they can get in.
Sat nav engineer - I optimise the raw map data for one of the world’s largest producers of personal navigation devices. We use Google Maps to calibrate our data.