be as slippery as an eel
To be devious, scheming, and untrustworthy—and difficult to apprehend. Of course that guy took everyone's money and left town—he's as slippery as an eel! Companies like this are slippery as eels, coming up with all sorts of elaborate means of getting around regulations. Their embezzling CEO has been slippery as an eel, but we've finally got some hard evidence on him now.
Farlex Dictionary of Idioms. © 2024 Farlex, Inc, all rights reserved.