Clean as a whip

I am having trouble finding the origin of the phrase "clean as a whip". I am unable to find it anywhere on the web.

I have heard "smart as a whip" and
"sharp as a whip" but I have never heard clean as a whip. And I, like you, am unable to find anything concerning the phrase you posted.

Within what context did you see / hear the phrase?

Sounds like somebody mixed up smart as a whip and clean as a whistle. At least it sounds more probable than smart as a whistle. ;-)