I used to work for a German dating site called friendscout24 when it was still in it's early stages. we worked with a psychologist to help improve the quality of the match-making logic (now be2.com). I didn't really care too much about the product back then and was mostly trying to scale the backend which was my passion. Linux, Java lot of traffic and scaling issues everywhere in these pre-cloud days.
The whole thing was built with affiliate marketing and also engineering was increasingly driven by the marketing team and their sometimes outrageous ideas. I remember the best idea that we had was to move to recurrent billing (profits went through the roof because people forgot to cancel the service) and not long after, it was acquired by T-mobile. That's when I left since the work suddenly was all about internal API's and not really interesting for a nerd like me.
The craziest place at friendscout was the customer care. We had one student working there who did a master thesis in psychology and chose sado-masochism as subject. She was on a roll there with all the people asking crazy questions to customer care. She was kind of a student of the human condition I think and I had some very cool conversations in my time there. Friendscout wasn't targeting this (S/M) niche.
However there were plenty of users that came from all sorts of dark corners and S/M was by far not the darkest. One guy (he was internally called the shit-eater because well no need for explanation) kept coming back with countless new pseudonyms every week ("brownsauce", "smellyjelly", "sh1tinyourmouth" and other words, very hard to filter out upon registration). He was an isolated individual no doubt but kept half of engineering and all of customer care busy for weeks.
Most users were fairly normal though, albeit (looking back) vulnerable in a way that still makes me sad. At least those who engaged with the customer care.
They were men (mostly) that hardly ever had a girlfriend whose name hasn't ended in dot-jpeg or the type of girls that would "power"-date 7 guys in as many days to find their "perfect love". For many it was like tinder but without labeling it as a casual dating site. But casual hookups were probably the main use (at least for guys).
Since it was early days the product wasn't very specialized or settled into a specific vertical, that's why we had all types of crazy people mingle along "normies". (what is normal? I have no idea but I knew that place certainly didn't feel normal)
The shit my colleagues from customer care have seen though was another level. Once they compiled the craziest stories into a book (verbatim conversations from users copy pasted for the amusement of staff) and handed it out to all employees as a Xmas gift. It was funny admitted but hardly ethical to put these customer-support emails into a book and then laugh about your stupid users at a company gathering.
Thinking back, my biggest regret about the place was not leaving earlier.
After the acquisition the founders also moved on to other projects. Founders were relocating their personal assets to Switzerland and learned how to capture all of the market. They formed various shell companies (e.g. Insparx in Luxembourg) through which to bootstrap much darker and more sinister "dating" ventures. They formed a company called c-date (c = casual dating which was the German front for Insparx). This allowed them to capture the lower segments of the market while keeping their names clean and also save some cash by funneling services through the low-tax structure instead of Germany. They also pushed into the upper segments like match.com (total market domination seems the point for any company so be careful what you get into because eventually they'll pivot into new domains and bootstrap it with what they have) ... but this isn't what I'm talking about here.
According to one of my old colleagues from friendscout who moved on with the managers to build C-date (again actually Insparx), C-date was using the affiliate marketing scheme they had at friendscout but applied in this way: advertise on websites for women (fashion magazines, interior design, basically all the Grune+Jahr publishing brands - most of Grune+Jahr were also affiliates with Friendscout). The messages women saw when visiting burda.de would be something like "looking for Mr Perfect?" or some other drivel that only fashion magazine readers would be gullible enough to respond. The women would click on it and sign up in an iframe of the original (girly) site (and not have a clue that this was c-date). And men would be targeted with a more honest and different message (on xhamster, redtube, youporn ... you name it) which read: "looking for horny sluts in your area that just want to get f!cked - click here ". Absolutely fucking degrading.
Both Jan Becker (and his mentor & former friendscout CEO Andreas Etten) managed to keep their names out of controversy and am sure are well respected individuals of the Munich & Zurich tech scene. But they're until today the names behind the Luxembourg shell companies and who signed off on these predatory strategies. They (and others) deserve to be burned at the stake for tricking these female (and quite frankly male) users with these growth hacking techniques.
If you have read this from beginning to end you might have noticed that it all started out with good intentions: Bring people together based on match making rooted in science. It ended as one of the most disgusting things that I've ever come across. Meanwhile I've seen countless similar ideas go from best intention to a dumpster-fire (sharing economy LOL). Whenever somebody claims that their idea will make the world a better place, run!! Because these are the worst.