Season five premiered on Wednesday night, but the 24-year-old has already earned a mild amount of fame thanks to her appearance in ads promoting the show.

Here, Costa meets this year's bachelor, the distinctively named Matty J, wearing a gown with bum-exposing sheer panels up the sides. As a fashion trend, it's not new (Gwyneth did it years ago). But you can't help but notice, all the same.

In an interview with News Corp this week, Costa explained she didn't realise "how naked" she was until she saw the promos. Then again – context alert – she was rarely in underwear during the filming of the show, presumably because of the continued evening wear demands.

"I think there was only one week where I did," she said. "I think most of the girls in most of the weeks were not wearing underwear."

Ladies and gentlemen, welcome to The Bachelor, a show that does more to set the feminist cause back than anything else on Australian TV.

It works like this: an unlucky-in-love man who likes showcasing his abdominals is selected as the bachelor and a collection of twentysomething and thirtysomething women are chosen to compete for his heart.

While it has already been pointed out that the women are overwhelmingly white, they are nevertheless a diverse bunch. One contestant, Simone, can reportedly fit 25 marshmallows in her mouth, another works as a body painter. There is a lawyer, a love coach and Lisa – a model – who has been introduced as "the one wearing the stunning red jumpsuit".

In the first episode, the women are presented to the bachelor wearing outfits that look as though they were designed by a high school textiles and design class and are encouraged to do unusual things (like cartwheels, ruffle his hair, sing a hideous song) to attract the bach's attention in this crucial moment.

The 22 are housed (kept?) in the "bachelor mansion" bedecked with rose petals and candles. They hang out here by day, desperately hoping to be picked for a group or one-on-one date by the bachelor. By night, they dress up again in their undie-less gowns for cocktails. Here they drink, bitch about the other women and manoeuvre to get time alone with the bachelor (this involves subtle moves like grabbing his hand and leading him away).

As the promos gush for season five, Matty J is an instant and unquestioned hit with the women: "He's gorgeous," says one candidate. "He's got some good guns under there," notes another. Consequently, the bachelor has a lovely time while women fall all over him. And fall over each other, trying to get to him.

It's a televised harem.

The Bachelor is one of Australia's most popular and talked about shows, particularly in the 25-54 demographic. Last year, more than 1.3 million people watched Richie break Nikki's and the nation's heart by choosing Alex in the finale. It trended as No.1 on Twitter worldwide and had an average weekly reach of 4.2 million on Facebook.

Most people who watch it would insist they don't take it seriously. It's a chance to flop on the couch with a glass of wine and an opinion, while other people embarrass themselves. The show reliably produces outrageous behaviour that makes you feel like you've got your life together by comparison. And it's beautiful to think that we might be watching yee-hah everlasting love evolve before our very eyes.

For all the above reasons, I tuned in to The Bachelor on Wednesday night. But I'm not proud of it. Because it's a show that makes women look stupid for our entertainment. They are put in an undignified situation and so (surprise, surprise) in many cases, behave sans dignity. As they parade around in gowns and bikinis, during the inevitable pool and beach dates, the women look one-dimensional and powerless. As willing desperadas, waiting passively for a man to please notice them.

The natural counter-argument here is what about The Bachelorette? Surely women get their own back when single lady Sophie Monk picks from a bevy of eligible guys later in the year. Apart from the fact that the tone of The Bachelorette is different (the men in previous seasons seemed more interested in mucking around with each other than competing for the affections of the woman in question), two duds don't make a right.

It's also arguable the only things hurt in the process are a few hearts and egos. The women on The Bachelor want to go on the show and get a few minutes of presumably much-wanted fame. Two people get a relationship out of it and the rest of us get some TV to watch.

But the show is so popular and so pervasive that its olden times approach to male-female relations can't help but be normalised in the process.

It's just a bit of a laugh, sure, but why do we choose to have our fun this way?

Judith Ireland is a Fairfax senior writer.