Following up to comments and requests below… I wrote an article about this a while ago, which you can find here (save a little room). In addition, the case law and analysis is also updated and dealt with in our book on prosecution ethics). Finally, then-Director Moatz’s paper is here (MoatzPTO Day), where he talks about it. There is at least one subsequent disciplinary case, too, that I recall, but couldn’t find.
Here are two OED cases related to this issue:
And some more:
In re Watkins, (Dir. U.S. Pat. & Trademark Off. Proc. No. D06-04 June 18, 2008); Va. State B. v. Lynt, in the Circuit Court for the City of Alexandria, Va. (Chancery No. CH04001593, Sept. 15, 2004), related proceeding, In re Lynt (Dir. U.S. Pat. & Trademark Off. Proc. No. D05-05 undated).