describing tradeoffs that would seem reasonable to most people
(Transcript...)
Cueball: Spammers are breaking traditional Captchas with AI, so I've built a new system. It asks users to rate a slate of comments as "Constructive" or "Not constructive."
Cueball: Then it has them reply with comments of their own, which are later rated by other users.
Megan: But what will you do when spammers train their bots to make automated constructive and helpful comments?
Cueball: Mission. Fucking. Accomplished.
(from https://www.explainxkcd.com/wiki/index.php/810:_Constructive)