“She’s so stupid, she slept with the writer” (casting joke)

To be cast in a Hollywood or a Broadway production, the old saying is that a starlet sleeps with the director to get the part. “She’s so dumb/stupid, she slept with the writer” is a jocular saying illustrating the lowly place of a writer in a production, especially on a Hollywood set.
     
“One of the oldest inside jokes out there is of the starlet so dumb she slept with the screenwriter in hopes of advancing her career” was cited in the book None But a Blockhead: On Being a Writer (1986) by Larry L King. Although the screenwriter joke was very popular in the 1980s, it is probably much older.
     
         
Newspapers.com
15 April 1981, Nanaimo (BC) Daily Free Press, “ShowBiz: The Woman Who Really Shot J.R.” by Rick Du Brow, Wednesday Niter sec., pg. 7, col. 2:
She (Loraine Despres—ed.) also, however, has a healthy skepticism about the realities here, noting the old line about “the starlet who was so dumb she slept with a writer.”
     
February 1982, Cosmopolitan (New York, NY), “Screen-Writers: The Stars Behind the Stars” by Lawrence Eisenberg, pg. 294, col. 2:
The powers that be may all publicly proclaim that success is in the written word, but, even if this is true, the hierarchy of the motion-picture business doesn’t reflect it. ICM agent Sam Cohn, one of the giants in the business, quips, “Did you hear the one about the lamebrained actress who wanted to get ahead? She slept with the writer.”
 
3 March 1985, Washington (DC) Post, “Hollywood’s Script Doctor: Tom Mankiewicz, Tonic for Ailing Screenplays” by Paul Attansio, pg. G1, col. 1:
There is an old Hollywood joke, setup and punch line at once: “Did you hear about the actress who slept with the screenwriter to get a part?” Such is the paradox of writing for Hollywood, where everyone agrees that only good screenplays make good movies, yet screenwriters themselves are the least powerful men in a business that knows only power.
 
Newspapers.com
6 February 1986, LA Weekly (Los Angeles, CA), “Have you heard the one about the honest agent?” by Christopher Monger, pg. 33, col. 4:
While Hollywood jokes may tell us a lot about the current state of the business and the attitudes of its participants, they are equally revealing in what they don’t talk about. I have already observed that there are few jokes about directors, and have rarely heard any about actors, unless you include the one about the actress (your choice of ethnic group0 origin who wanted to get ahead in Hollywood. (She slept with a screenwriter.) 
 
Newspapers.com
17 August 1986, Chicago (IL) Tribune, “Screenwriters get little credit, but the pendulum starts swinging in their direction” by Julia Cameron, sec. 13, pg. 12, cols. 2-3;
Screenwriters themselves tell a joke about the ambitious but dumb starlet who came to Hollywood determined to make it big in the movie business. Her big move? “She slept with the screenwriter.”
 
Even among feminist screenwriters, this joke meets with rueful guffaws. Sexual politics are one thing, but studio politics are something else—and something worse. As one feminist screenwriter succinctly phrased it, ‘“In the world of studio politics, screenwriters as well as starlets are f——-.”
 
Google Books
None But a Blockhead:
On Being a Writer

By Larry L King
Hamondsworth, Middlesex, England: Penguin Books; New York, NY, U.S.A.: Viking Penguin
1987, ©1986
Pg. 212:
One of the oldest inside jokes out there is of the starlet so dumb she slept with the screenwriter in hopes of advancing her career. That joke not only defines Hollywood’s social pecking order, it says more than I’d like to admit of the writer’s ...
 
Google News Archive
8 June 1988, Glasgow (Scotland) Herald, “Hollywood strifes” by Anne Simpson, pg. 12, col. 7:
And, indeed, if anyone has a real cause for revenge in Hollywood it is the creatively fleeced, and often uncredited, scenarists who for years have been labouring under that cheap, humiliating barb about the movie starlet who was so dumb she slept with a screenwriter.
 
New York (NY) Times
Anatomy of a Sitcom
By Linda Blandford: Linda Blandford writes from Los Angeles for The Guardian of London
Published: April 02, 1989
(...)
Writers, as everyone knows, are the lackeys of the film industry. (The starlet joke goes: “She was so dumb, she slept with the writer.”) The exception is situation comedy. They call it ‘‘the voice,’’ ‘‘the melody’’ and every successful show has one.
 
Google Books
Crafty TV Writing:
Thinking Inside the Box

By Alex Epstein
New York, NY: Owl Books (Henry Holt and Company, LLC)
2006
Pg. XIX:
You heard the old joke about the dumb actress in Hollywood — she slept with the writer!
 
Google Books
Authorship in Film Adaptation
Edited by Jack Boozer
Austin, TX: University of Texas Press
2008
Pg. 70:
As the old joke about a Hollywood starlet so dumb she slept with the writer attests, screenwriters are widely perceived as the least powerful collaborators on movies.
 
Google Books
Mrs. Nixon:
A Novelist Imagines a Life

By Ann Beattie
New York, NY: Scriber
2011
Pg. 121:
RN was also the scriptwriter (old joke in Hollywood: “She was so stupid, she slept with the writer”).
         
Twitter
Steve Sailer
@Steve_Sailer
From my review of “Mank,” w/Gary Oldman as the screenwriter and Amanda Seyfried as Marion Davies:
 
“In the movie industry, they joke about the blond starlet who was so dumb she slept with the writer, but Marilyn Monroe married playwright Arthur Miller.”
https://takimag.com/article/that-touch-of-mank/
5:37 AM · Dec 9, 2020
   
The Cinemaholic
What is the Screenwriters’ Joke in Mr. Harrigan’s Phone?
Sumith Prasad
October 5, 2022
(...)   
The real joke Harrigan refers to reads, “One of the oldest inside jokes out there is of the starlet so dumb she slept with the screenwriter in hopes of advancing her career.” The joke, which was probably conceived after the emergence of Hollywood in the 20th century, sheds light on the influence of screenwriters during the period. At the time, the motion picture industry was ruled by the heads and executives of potent filmmaking studios. Even the directors were lesser powerful people on the set. The studio heads and executives had the final say in selecting cast members and establishing them as stars.
   
Halloween/Horror Transcripts
Mr. Harrigan’s Phone (2022)
Post by bunniefuu » 10/06/22 18:58
(...)
You spoke of screenwriting,
and if it’s what you want,
 
then, of course, you must pursue it
but know that I do not approve.
 
There is a vulgar joke
about screenwriters.
 
I will not repeat it here,
 
but by all means, find it on your phone.
 
Keywords “screenwriter” and “starlet.”
 
Screen Rant
The Screenwriter Starlet Joke In Mr. Harrigan’s Phone Explained
Netflix’s Mr. Harrigan’s Phone references a dirty joke about a starlet and a screenwriter, but what’s the joke and what does it really mean?

BY CATHAL GUNNING
PUBLISHED OCT 11, 2022
(...)
Mr. Harrigan is obsessed with power and obliquely informs Craig that there is no power to be gained as a screenwriter by telling him to look up an old joke about screenwriters and starlets online. The joke isn’t revealed before the ending of Mr. Harrigan’s Phone, but the real-life gag is about “the starlet so dumb that she slept with the screenwriter.” Ultimately, the joke is intended to illustrate that screenwriters are the least powerful people in Hollywood and plays into the movie’s themes around the pursuit of power and its preeminence in Mr. Harrigan’s mind. In this way, what seems to be a throwaway line actually helps strengthen the underlying message of the film.