I think anyone on this forum who writes an email to one of these professional liars, doesn't really believe they are going to win friends and influence people.
However, I think it can be cathartic, letting the hack know you have his/her number and that they can't fool all of the people all of the time with their distortions and weasel words.
From personal experience, I think that might be the best you can hope for...just "a twitch upon the thread" of their long departed decency and integrity, as Evelyn Waugh might say.