Related Clues:
- Cafeteria mishap
- Exxon Valdez calamity
- Waste (liquid)
- A biker may have a nasty one
- Engrained dirt
- Dirty gunk
- Dirt, for example, seen back round edge
- Dirt, dust, soot, etc
- Filthy buildup
- It gets mopped up
- Reveal opening on someone's tablet
- Ingrained dirt, dreadful by end of aisle
- Stubborn laundry dirt
- Sloppy floor covering?
- Overturn milk