1. extremely filthy from long neglect
The Collaborative International Dictionary of English v.0.48:
Augean \Au*ge"an\, a.
1. (Class. Myth.) Of or pertaining to Augeus, king of Elis,
whose stable contained 3000 oxen, and had not been cleaned
for 30 years. Hercules cleansed it in a single day.
2. Hence: Exceedingly filthy or corrupt.
Augean stable (Fig.), an accumulation of corruption or
filth almost beyond the power of man to remedy.
WordNet (r) 3.0 (2006):
adj 1: extremely filthy from long neglect