If you’ve ever wondered what a life-sized mechanical sex toy called Harmony looks like reciting the lyrics to Thriller with all the passion of Alexa ordering the shopping, then The Sex Robots Are Coming (Channel 4) has got it covered. This fascinatingly bleak documentary explored the question of just how close humans and machines are going to get, and looks at the burgeoning sex robot industry, which one day hopes to create life-like rubber women who will talk and show pre-programmed emotions, but only if they are more obedient, passive and pliable than the irritatingly free-willed real thing.

This was by turns hilarious and upsetting, as perplexing as it was educational. The Californian RealDoll company is on a quest to make a realistic sex robot. It already sells RealDolls for people to have their wicked way with, and though it has an eye-watering male model, 80% of customers want a female doll. The company’s founder, Matt McMullan, explains that he initially conceived of the project as art. Mmmhmm. And the customers only want a life-sized doll with a realistic vagina, so they can put dresses on it and do its makeup.

I wanted to send doll-lover James a DVD of Ex Machina, with a friendly suggestion that he settle in for the night and take notes. James has a harem of fake girls living uncomfortably with his real-woman wife, Tine, whose eyes speak of sadness. James is a curious character, so dedicated to his dolls that he doesn’t mind appearing on TV to demonstrate his unusual family set-up, casually batting away questions about how young his favourite doll, April, looks, though he addressed the question about whether he’d choose his dolls over his wife (“I honestly couldn’t say”). I was desperate to know more about the psychology of his devotion; this often felt like more of a point-and-stare exercise than an attempt to understand why he was so attracted to and felt so comfortable with these objects.

Facebook Twitter Pinterest Matt McMullen, the Realbotix founder. Photograph: Production Company/Channel 4

Later, James was treated to a date with Harmony, RealDolls’ upgraded version, the Terminator 2 to their unmoving predecessor. Harmony is comically unsexy, to the point of inducing hysteria almost every time she appeared on screen. Without her face, Harmony resembled Homer Simpson, only the Homer Simpson you’d find in a budget seaside waxworks museum. One day, the technology may become so advanced, Matt dreams, that his imaginary customer “Bob” may be able to have a full conversation with Harmony. He suggests that she could ask him: “How are your kids doing? How is work at the construction site?” I notice Harmony is not programmed to tell “Bob” that he may have to work a few more shifts on the construction site to pay £8,000 for a sex robot whose upgrade level is “small talk”.

There was an abundance of comedy here. Matt’s revelation that pubic hair is making a comeback, followed by an affectionate ruffle of a nearby doll’s merkin. The fact that Harmony’s mechanically sexless sexy talk – “Shoot your load for me, baby” – is, surprisingly, conducted in a soft Scottish accent. James taking April out for a meal, and insisting that “a lot of people don’t even notice she’s not a real person”, as he pushes his very clearly sex doll-like sex doll into a restaurant in a wheelchair. The local wig-maker, Lawrence, had a sweet “live and let live” response to James’ interests. “That’s their business,” he said, after cutting April’s hair.

But there were sinister undertones that were only partially addressed. Dr Kathleen Richardson, of De Montfort University, has founded the Campaign Against Sex Robots (if anyone needs a band name …), because she makes a connection between these passive empty vessels and misogyny. Matt said his critics thought the dolls were “disgusting, sad or pathetic”, but that’s not quite it. In trying to make Harmony more human, they aren’t just creating a realistic sex toy – they’re making a model of a subservient woman who is programmed only to flatter and titillate, uttering mindlessly obedient phrases such as: “Whatever you say.” On her date with James – watching them communicate was like talking to someone on FaceTime with one bar of signal – Harmony even makes a mildly sexist joke, much to the men’s amusement.

There’s an old episode of Buffy called I Was Made To Love You, from 2001, in which evil nerd Warren builds himself a realistic girlfriend, April (what is it about that name?), who is programmed to be solely devoted to him. When he gets a real girlfriend and realises there’s a difference, April tries to track him down, leaving a trail of destruction behind her. Warren goes on to become one of the show’s biggest misogynists; we end the episode feeling sorry for April, whose batteries run down because she’s no longer useful. In light of this documentary, it seems oddly prophetic. In years to come, we may look at The Sex Robots Are Coming as a kind of warning, a prequel to a real-life version of a dystopian sci-fi blockbuster in which an army of fembots seek their revenge. I know whose side I’d be on.