Those are typical bots and those bots only do what bots do best: they comment without looking at the content in the hope that somebody will upvote it and thus generate free money for their owners. On https://steemit.com/curration/@mattockfs/results-of-steempersist-paywalhater-script-test-run there are a few scripts posted to detect bots and even to downvote those comments but that experiment in itself led to a real shitstorm.