I've worked in a lot of different jobs in the twenty-three years that I've been alive, and my husband has done a few as well. Some of the dirties though were:
Animal Caretaker with the Humane Society
-entails cleaning the cages/litterboxes of the animals, feeding them, and giving them medications daily...all of which can be very, very dirty jobs.
Hotel Porter/Housekeeper
-cleaning rooms/bathrooms in hotels...the porter can be especially dirty if it's a large group and there was a lot of drinking, but the housekeeping itself is undoubtably worse. One room I cleaned had the bed coated with blood, and scrawled on one wall was the message 'Thanks, we had a great time'. Another room had been trashed during a football watch party, and one person had gotten drunk enough to start vomiting in the main part of the room and continue all the way into the bathroom...hitting the floor, walls, sink, toilet, and bathtub during all of it.
Wharehouser
-this is largely what it sounds like, helping to store and retrieve items from warehouses...but those places can be highly dusty, and aren't the cleanest atmospheres.
Butcher
-other than the Humane Society, this was definately the dirtiest. While you might occassionally get blood on you at the hotel, you were guaranteed to get blood on you constantly as a butcher, while working in a very cold environment so that the blood would sometimes freeze to your clothing.
Auto Salvage
-tearing parts off of cars sound like an easy job? Get ready to get dirty if you're working here, as there's a lot of grease, rust, and oil to coat yourself with. Oh, and look out for sharp edges.
You know...after going back and re-reading some of these other posts (Herring Squeezin and the ones about slaughterhouses in particular)...maybe these jobs aren't dirty enough.
Then again, I've helped my dad slaughter and butcher cows on our farm, as well as chickens and pigs, so I have a decent idea on those messes too.