In Backpage's defense, they were instructed to block those words by their legal team and law enforcement, as those words are not allowed to be posted because they indicate sexual favors in exchange for money, i.e. prostitution.
But Backpage actively helped these guys create ads that won't trigger any red flags. Instead of blocking the posts, warning them, or straight up banning them, the listing wizard directly suggested ways to conceal illegal activity after detecting 'bad' keywords, in order to help allow the user to continue to use the site.
This feature most likely had good intentions for other law abiding users, likely for the largely majority of cases, but it was pretty damn obvious how it also helps some seriously bad guys. You'd just have to look at some of the example keywords which would trigger this automated assistance...
Backpage played an active role not just a reactionary passive one. Which is why I understand and support legal action against them - although I'm not sure seizing is the right approach, but that's another story.
1) Paying customer creates an ad (I haven't used Backpage, but I assume they paid to create ads).
2) Paying customer enters some words that the Government has told Backpage not to allow.
3) Backpage's automatic web form error message says... "Hey, you've added some words the Government won't let you use... sorry... it's not us, it's Uncle Sam."
4) Customer changes words to get around filters... I assume things like "sex" turns into "s3x" -- or whatever the bare minimum number of changes were to get around the censorship.
5) Customer posts ads, skirts Government censorship; feels smug and satisfied for beating the system.
6) Government isn't happy that the intent of the filtered words wasn't enforced... expected Backpage to have more (costly) manual review of ads, instead of just exact keyword blocks on ad creation.
7) Backpage was like, "Manual review would destroy our business model..." so they fought it...
8) Government took over and shut them down.
Again, I haven't read anything on this... but that's my assumption based on how the Government and tech work. Am I wrong?
Instead of just assuming, if you don't want to read it all, read just pages 2 and 3 (summary).
https://www.hsgac.senate.gov/imo/media/doc/Backpage%20Report...
Posting ads for escorts which clearly indicate an underage girl or similar is obviously not something you want on your site.
In fact I don't see anywhere this has to be a list of keywords defined by the government at all?
And as the other user pointed out, it's far worse than a simple form error.