Action to remove all unused swatches nearly works...

I've been using the default Action to remove fluff (unused swatches, symbols, brushes, etc.) but it has a funny quirk. I have a spot black color (named black) that always escapes the purge, even if it not used in the document. It is not set as the default stroke/fill, and there are no styles that use this swatch. Even if I run the Action twice the swatch remains. Even if I rename the swatch to something other than black it remains. Even if I rename the swatch and give it a different CMYK mix it remains. As a kludge, I've been using a combo of the default action and John Wundes' Delete Fluff script to get everything, but it is not an ideal solution. Wundes' script, which is unable to delete used brushes, roots out the offending swatch. It is unable to delete unused brushes, so following up with the default action clears those out. Also, Wundes' script is very slow and will often beach-ball the application, requiring a force-quit occasionally.

Two questions:

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Can anyone think of other places that might harbor this rogue spot color and make the default action not find/delete it?

Is there a simple script that could check specifically for the use of this color in the document and delete it?

Cheers and thanks!!

-G-