Cheating on one’s spouse is pretty lowdown. What’s even worse? A business that encourages and profits off of it.

But, wait, there’s something even worse than that: How about a business that encourages infidelity, uses bots and fake profiles to boost membership and falsely assures its clients that their private information is secure?

That is the absolute worst, andthatwas Ashley Madison.

The online dating site, expressly for married people looking for sex with other married people, is the subject of a ABC News Studios three-part documentary, “The Ashley Madison Affair,” released Friday, July 7 on Hulu — and it is compulsive viewing. Do not start watching it if you don’t want to watch the whole thing.

Ashley Madison launched in 2001 and took its name from the two most popular baby names at the time, “Ashley” and “Madison.” Right away, that’s creepy. But the business really hit its stride with the ascension of Noel Biderman to chief executive officer in 2007. From the start of his reign to 2015, Biderman was the face of the company and appeared on a variety of talk shows, including “The View.”

It’s not enough to say that Biderman was not the most likable person; an example is required. At one point in the documentary, he appears on screen being interviewed on Fox News’ “Hannity,” and by comparison, Sean Hannity seems like a swell guy.

A large part of “The Ashley Madison Affair” is Biderman’s story, and much of what keeps viewers glued to the screen is looking forward to his downfall, which came in 2015, when Ashley Madison was hacked and its client information was released to the internet.

The documentary traces the growth of Ashley Madison, which used audacious advertising to entice customers. The sleaziest print ad featured Biderman’s wife, Amanda, with the accompanying tag: “Your wife is hot, but so are ours.”

The business model of Ashley Madison is that men pay to use the site, but women can join for free. Yet, for some wacky, unexplainable reason, the notion of no-strings, emotionless sex didn’t appeal to nearly as many women as men. So to make the site look more attractive to guys, the company created thousands of fake female profiles, supposedly of clients looking for fun. This means that men, trying to cheat, were getting cheated.

They were also getting their confidence damaged, because they were writing to women who never wrote back. “Why doesn’t she like me?” they wondered. “Why do none of these women ever respond?” Little did they know these women had a very good excuse for being unresponsive: They didn’t exist.

The documentary contains interviews with people whose marriages were damaged or destroyed by Ashley Madison. Some were spouses of clients, some are former clients. There are also several actors here speaking the words of actual clients who didn’t want to reveal their identities. (The actors seem like actors. Real people are more self-conscious.)

During the company’s heyday, Biderman often appeared on talk shows with his wife, in which he said that their relationship was monogamous. But in the 2015 hack, by a still at-large group known as “The Impact Team,” his personal emails revealed that Biderman was using the site. At one point, he wrote that he was looking for girls who were 18 or 19 years old. Soon after this exposure, he ceased to be CEO.

Biderman’s marriage survived. Even more incredibly, the business survived. After the lax security, the fake profiles, the public embarrassmentandthe subsequent lawsuits, people not only want to buy what Ashley Madison is selling — they’re still willing to buy it from Ashley Madison.

Reach Mick LaSalle: mlasalle@sfchronicle.com