Not the commenter you asked, but for me I often find it in Google alerts, where to legitimize the site they have front-loaded it with real text scraped from legit sites.
I won’t go too heavily into details, but I’ve had them come up with rather innocuous sets of words, ones that, horrifyingly, a young child would be likely to use. And if you include drawn media alongside photographic abuse material then it can be as simple as looking up characters from a cartoon.