The fact is that nations simply do not send 'public sinners' as Ambassadors---or didn't; it was an insult. Some ambassadors (and others) of course, turned out to be rather horny--and often were removed.
Seek proof? If the 'bad guy' public figures were convinced of the rectitude of their actions, then they most CERTAINLY would not be clandestine.
Who is being clandestine? If you are referring to Ambassador Guest, the subject of the article, no one has accused him of being clandestine.