Back in the day I did work at a group of one of the largest adult websites.
Tech was PhP, MySQL, memcache and similar vanilla stuff running on many Linux servers - pretty simple stuff.
The trick was performance. Simple stupid mistakes that would not be detected in sites that have low traffic become enormous problems in a high traffic server.
Pretty much nothing was dynamic and we wrote scripts to create static pages for almost everything except search and authentication.
Things like logging just could not be done. It was easier to load a bunch of data in memory on a request and process it instead of running a slightly slower SQL query, since a ton of those could kill the database.
And yes, there were no placeholder images or videos. After some time you just get used to it and code. But I have to say you get pretty desensitized to it and when I resigned from that job my life in that area improved quite a lot.
Highlights were p*rn stars and random celebs visiting the office - but after some time that got kind of meh.
The job itself was just a programming gig and very professional except for the images on the screen which we learned to ignore.
On the whole, the guys who ran the thing were a pretty solid and great bunch of people and it was one of the best dev experiences in my long career.