Marketers Flood Reddit With AI Posts to Manipulate Chatbot Answers

A study published December 11, 2025 by AI-detection firm Originality.ai estimated that 15 percent of Reddit posts were 'likely AI-generated' in 2025 (rounded from 14.7 percent), up from 13 percent in 2024 and building on a measured 146.30 percent increase between 2021 and 2024. While a single-firm detection study with methodological caveats, it became a widely cited data point in the 'dead internet' discourse about Reddit being increasingly populated by machine-written content.

The most concrete documented case emerged on June 3, 2026, when 404 Media reported that peptide and hormone-replacement-therapy companies had been doing AI-engine optimization by spamming the biohackers subreddit to manipulate ChatGPT and Google. The practice, Answer Engine Optimization (AEO), targets the source material large language models scrape. The moderators of r/Biohackers announced they would ban new standalone posts about peptides and HRT, limiting discussion to weekly megathreads, writing: 'As AI search engines increasingly pull answers from Reddit, companies are using us for AEO (answer engine optimization). On top of that, there's been an explosion of peptide interest and AI usage flooding the sub. Together, this has put serious pressure on content quality.'

Moderators described tactics subtler than traditional spam. Companies 'reverse-engineer the actual prompt patterns that are prioritized by LLMs,' one moderator said, seeding clickbait questions such as 'Is all the hype around Vitamin D actually worth it?' so that brand mentions could be worked into high-engagement threads AI systems are likely to cite. The accounts involved were 'warmed up' profiles with organic-looking posting histories, and in some cases real people were paid to participate. The moderator framed the stakes bluntly — 'how do we prevent actual physical harm?' — and mourned that 'this one place on the internet that was so human is sort of eroding and becoming bogged up with artificial AI-driven content.'

Reddit told 404 Media it relies on a combination of human review and automated systems to detect and remove manipulative content, and that moderators have access to tools designed to flag likely spam accounts. Its transparency report covering January to June 2025 recorded 158,025,279 pieces of content removed by mods and admins, with spam accounting for 57.5 percent of admin removals and content manipulation, including vote manipulation, a further 0.6 percent, though Reddit also noted an overall decline in spam attacks over that period.

By August 2026 the authenticity question had reached Reddit's investor story. CEO Steve Huffman told shareholders that 'as the internet becomes flooded with synthetic content, people are craving real human perspective. We are the antidote to an automated web,' adding, 'We've never had more information, but we've never trusted it less.' Reddit's shares nonetheless fell more than 20 percent after the earnings report, with search referrals 'choppy' in Huffman's words, and a Wall Street Journal report said Reddit was considering ending its $60 million licensing deal with Google.