> I've never heard anybody complain about their ads showing up on a porn website.

Then you've clearly never worked in media or advertising.

Most advertisers would be livid if their ad showed up on a porn website. Many of them will even be upset if you put their ad on a slightly risque article.

They don't want their image associated with porn (or tragedy). Even legitimate mainstream news organizations have to put in code to exclude advertisers from certain article categories.

> Even legitimate mainstream news organizations have to put in code to exclude advertisers from certain article categories.

And see eg Private Eye's "Malgorithms" or Need to Know's Doh! gifs for examples of poor ad placement.

Advertisers are usually very wary of what content is associated with them. I'm sure the morally conservative vocal people would complain to the brand or something like that. Or maybe not, if that would imply that they were watching porn...