Katherine Heigl and Seth Rogen share an awkward meal in <i>Knocked Up</i>.

Katherine Heigl and Seth Rogen share an awkward meal in Knocked Up.

Cinema expects a lot of its viewer, namely the suspension of their disbelief. It’s how we can accept, as audiences, that a computer generated world of big blue cat aliens is instead a living, breathing forest (Avatar), or that Ashton Kutcher can act (pick a Kutcher film, any Kutcher film).

The mere fact that we can sit through a film, for entertainment’s sake, without barking “WHAT IS THIS SORCERY?” is suspension of disbelief in its purest form.

If there is one recent filmic development that relies on such outrageous fantasy that suspension of disbelief goes out the window, it’s the “schlubby guy gets the beautiful girl” romantic comedy trope.

Jay Barucheland Alice Eve in <i>She's Out Of My League</i>.

Jay Barucheland Alice Eve in She's Out Of My League.

You could argue that it has always been around, but it’s really taken hold in the Judd Apatow era of comedy, in which men can be spongy and hairy (Seth Rogen in Knocked Up, Jason Segel in Forgetting Sarah Marshall and The Five-Year Engagement), or skinny and weird/wired (Jay Baruchel in everything).

But hand-in-hand with this trend is another emerging eye-roller, the glut of “extraordinarily beautiful Hollywood actress plays a plain/goofy girl with low-self esteem” roles. What’s more sinister about this is that it’s the flipside to the aforementioned schlubby guy brigade - there are no (mainstream, at least) flicks where the daggy or ugly girl gets the beautiful man.

Why? Because nobody would buy tickets to see a film that stars a genuinely ugly, plain, or just different looking actress. Consequently, we are expected to buy ‘Hollywood-attractive’ actresses as they give it awkward.

Ashley Fetter explored this in an Atlantic piece, Why Do So Many Pretty Female Comedians Pretend They’re Ugly? It’s more understandable in standup comedy, where - as the piece notes - “young, attractive female comics in the stand-up industry have always been targets of sexualized heckling. Even today, "They still have people screaming at them, 'Take your clothes off!' [...] or "'Shut up and show me your tits!'”

In film and television, on the other hand, it’s jarring. It’s patently obvious to anyone with eyes that Tina Fey is a terrifically attractive woman, and yet we’re expected to buy that Liz Lemon is such a hopeless case that she’s romantic kryptonite.

Anna Breslin’s compelling essay The Unf-ckables examines the difference between Fey et al’s playing ugly and the reality for those actresses and comedians who are actually “ugly” (in Hollywood terms).

As Breslin notes, “While Fey may play at being dumpy on 30 Rock, the fate of her peers who are actually considered unattractive by the entertainment business is markedly more dismal. Her SNL castmate and friend Rachel Dratch was often used on the show for desexualized and unappealing characters, like an inbred freak or pre-adolescent boy. In 2008 she left Saturday Night Life after 11 years to commit full-time to her role on 30 Rock as Jenna Maroney. After the pilot taping, Fey and producer Lorne Michaels fired Dratch and replaced her with Jane Krakowski.”

Dratch can’t hope to find more actorly scope on the big screen, as that’s where the “beautiful actress plays dumpy” trope reigns supreme.

The latest example is The Low Self-Esteem Of Lizzie Gillespie. Written by Mindy Kaling, the rom-com is to star Anne Hathaway as Gillespie, “a woman whose lack of self-worth has limited her choice in men to losers. When she is about to hit the bottom of the barrel, life takes an unexpected turn when she is pursued by the hottest guy ever.”

Putting aside the obvious sick-making notion that all it takes to turn a life around is the love of a hot guy (though why anyone would expect anything else from Kaling, whose The Mindy Project is one of the more alarmingly retrograde TV comedies, gender politics-wise, to come along in a while), this is a tough sell.

The combination of concept and casting is, as they say, some bull****.

Now, I know it’s called acting for a reason, and there’s no rule that says a pretty actress can’t put on some glasses and play awkward (Oscar, in particular, loves it when A-list actresses dull down: Charlize Theron in Monster and Halle Berry in Monster’s Ball spring immediately to mind).

But if the men of the post-Apatow era can be fat, hairy, spongy and weird-looking, why can’t women?

Raunchy comedies like Bridesmaids and Bachelorette have “proven” (puhlease) that women can spew as many expletives and engage in as many body-fluid-related set pieces as their male counterparts, but the films are still populated by Covergirl-ready actresses.

Those who fall outside the accepted norm, like Rebel Wilson, are permitted to play the weird friend, but never the lead.

The danger in discussing this is that it can end up in an unpleasant pissing contest about which actresses are truly “ugly” enough to convincingly play it - but this isn’t about ugliness as much as it is striving for some sort of visual equality in our multiplexes. The fact is that there are countless actresses who don’t look like “movie stars” who would make outstanding romantic leads.

How good would it be, though, to switch the gender roles and see Wilson get the kinds of gigs that Seth Rogen gets? Imagine if Gabby Sidibe (who has, in Tower Heist and Seven Psychopaths, revealed herself to be a comedy natural) got the guy?

Then again, Hollywood relaxing its rigid beauty ideals and allowing all sorts of actresses to have their time in the sun? Now that really is a great joke.