I've got a unique one. It will take a bit of setting up. As part of our business breeding tropical fish, lots of water and gook from the tanks gets on the floor and is channeled toward grates. A series of PVC pipes embedded in the floor carry the water, dirt, fish waste, dead snails, uneaten food, etc. from the grates all over the building into one central spot, which is a pit cut into the concrete and lined with a plastic drum. There's a pump in here to drain out excess water. However, this particulate forms a silt that collects in this pit until it reaches the level of the pump and starts clogging it up. At this point the pit needs to be scooped out.
It's difficult to describe the odor. It's not a sewage smell, nor a dead fish smell. There's a component of ammonia to it, but it's a far more complex aroma than that. The uninitiated often have difficulty holding in their lunch the first time they're exposed to it. And of course you have to put your nose right up to it while you're bending down to scoop it out. And guess whose job that is.