This word sounds dirty and disgusting, but as that's what it means I suppose it's fair enough.
Feculent: filthy, scummy, muddy or foul.
Or, containing waste matter.
Word Not To Use Today: feculent. This word comes from the Latin word faeculentus, from faecēs, which is the plural of faex, which means dregs or sediment.
The other reason for not using this word, of course, is that no one will have a clue what you're on about.