| Clue | Source | Date |
|---|---|---|
| Like uncleaned pipes | ||
| Covered in filth | The Washington Post Sunday | 24 Mar 2019 |
| Covered in grease, say | Wall Street Journal | 16 Jan 2015 |
| Covered in grease, say | ||
| Covered in goo | ||
| Like many sluggish drains | ||
| Gooey | ||
| Hard to clean, maybe | ||
| Covered in goo | ||
| Covered in goo | ||
| Needing a good cleaning | ||
| Covered in goo | ||
| Gooey | ||
| Full of crud | ||
| Goo-covered | ||
| Like grease |