It means evidence in the form of blood or gore.
In Macbeth, a "filthy witness" refers to someone who has seen or knows about a crime or wrongdoing. This term reflects the idea that the witness's testimony or knowledge is tainted or corrupt due to the nature of the events they have witnessed.
The "filthy witness" which Lady Macbeth talks about washing from Macbeth's hands is, of course, Duncan's blood. "Filthy" because it is dirty and smells unpleasant. (Have you ever been covered in blood?) "Witness" because its presence on his hands marks him as the murderer--it testifies against him.
foul filthy
In Yiddish, you can say "אָפֿײַליק ריק" (oyfaylik rik) to mean "filthy rich."
For a pitcher to throw unhitable pitches. For Example Clayton Kershaw has a filthy slider.
Filthy could mean unwashed, begrimed, polluted, slovenly, verminous, depraved, or indecent.
filthy
A witness is someone who was present at an occurrence.
dirty, filthy, hard work
Filthy, Unsanitary, and Disgusting. If you want, you can go check a Thesaurus or go to the related link to look up synonyms for Filthy.
To drop something anywhere , OR a very filthy accomodation
It could mean anything !... My first thought was don't tell filthy little lies !