All three of the dirtiest jobs I can think of have been in the food industry.

First, the bakery of a large chain of retail stores making donuts, and accompanying duties. With the donuts, the worst was the glazing and packaging. You would get covered in this awful sticky mess up to your elbows. But that was nothing compared to cleaning/changing the grease, and cleaning the big dishwasher.

The grease cleaning, you would have to either filter all the burned crap out of the grease by running it through a filtering process, or take it out behind the store and empty it into a huge, stinky vat of grease that would be picked up and taken somewhere to be processed and used for things like cosmetics. Once, in the middle of August and the middle of the afternoon, cart thing that we had the heavy vat on to wheel it out sank into the asphalt and got stuck. We had to leave it there till the sun went down and the asphalt was cool enough that it wouldn't just sink in again to move it.

Cleaning the big industrial dishwasher and the drain system behind it was also a nasty, smelly job. The easy part was taking the inside apart, but once you removed the steel plates in the floor and drained the water underneath, you had to scrub the gelled, smelly undersides of the plated and all around the inside of the tank in the bottom to get rid of the old, waterlogged and caked on flour/grease mixture, then go around to the back of the machine where the water drained out under a grate and scrub that and be sure it was unblocked and able to drain, and it stank!

Then there is the produce department of the same store. Culling the old, rotten fruits and vegetables from the sales floor, cleaning (somewhat) and prepping the produce that comes in before you put it on the sales floor, keeping the back room/cooler clean when it's apparently all your responsibility and you are cleaning up after five men/boys, and cleaning the fresh squeezed orange jiuce machine after every use.

The rotten stuff is probably the worst of it, especially rotten potatoes and onions. There are few things that smell worse than a potato that has rolled way back under a shelf and had a good week or two to rot, getting good and slimy inside with the skin intact so that when you find it (usually by accident) and fish it out from under there with a long stick, you will probably break through the outter skin to release the nastiness within. It is absolutely awful.

The OJ machine is pretty tame by comparison, just very sticky abd citrus rind can get a bit oily and gritty when it's ground up in this machine. It's just more annoying and tedious to tear down the machine, pick the rind and seeds out of hard to reach places, scrub it all and put it back together. But, citrus juice and the oil from the citrus rind actually makes a good degreaser as I found out.

Working in an elementary school cafeteria is the worst, nastiest job, though. Not all of it, but working in the dishwashing room and then cleaning the dining room and the drains after lunch is pretty bad. In the dishwashing room, you take the dishes as the teachers and students bring them to the window and you dump everything into this big steel canal thing with water ruinning through it that is supposed to carry it along to the pulper, that grinds everything up and spits the soggy mess into a giant trash can. Sometimes the canal thing gets backed up, and as the trashcan gets filled up, you have to stop the pulper and put a new bag in the can so that oone bag alone won't be too heavy, or get another can altogether, you have to cut off the machine and let the trash build up a little bit while you are doing it. It seems like every single day, atleast one kid gets sick and throws up on their tray, sometimes more.

Then you have to clean the dining room, sweeping/mopping up behind a couple of thousand K-3 graders, washing the tables, ect. And the kid that threw up on his tray at lunch most likely missed the tray a good bit as well, so you have to clean that up off the floor, the table, and occasionally even the walls and take extra care to sterilize and sanitize those areas.

Of course, if you go to an elementary school cafeteria to film an episode, it might get even harder to get kids to actually eat in the school cafeterias.