Companies Spam Reddit With AI-Generated Posts to Manipulate AI Search Results

From 2024 onward, as AI search tools and chatbots increasingly cited Reddit (partly a consequence of Reddit's data-licensing deals with Google and OpenAI), a market emerged for manipulating those AI systems by poisoning their Reddit-derived inputs. The practice acquired a name, AEO or 'AI-engine optimization,' an evolution of SEO that targets the content sources large language models scrape and cite rather than the traditional search ranking. The outlet 404 Media reported repeatedly on firms seeding the user-generated sites AI tools most often draw from, with Reddit chief among them, with inauthentic promotional content engineered to be surfaced by AI assistants.

The incentive is structural. Between August 2024 and June 2025, Reddit was the single most-cited domain by both Google's AI Overviews and Perplexity, and the second-most-cited by ChatGPT. That centrality made Reddit the highest-value target for anyone seeking to shape what AI assistants tell users. 404 Media documented peptide and hormone-replacement-therapy (HRT) companies covertly spamming Reddit so their products would be scraped and recommended by chatbots; in response, moderators of r/biohackers announced they would ban new posts about peptides and HRT because of manipulation by the companies that make and sell them.

Cornell University researchers demonstrated how trivially such manipulation can be done. Their work showed that AI 'deep research' agents cite user-generated content in roughly half of queries, and that inserting as little as 13 words of planted text into a Reddit post could reliably steer an AI agent's output toward a chosen product, scam, or recommendation. The technique exploits the gap between how human moderators read a post and how AI retrieval systems ingest it, allowing content that looks innocuous to a human to act as a hidden instruction to a machine.

The phenomenon converged with broader 'dead internet' concerns about Reddit's content becoming increasingly bot- and AI-generated, and raised a strategic dilemma for Reddit itself: its most valuable asset is the perception that its content is authentically human, yet monetizing that content as AI training data creates a powerful incentive for bad actors to flood it with machine-generated, manipulative posts.

Reddit has said it deploys systems to detect coordinated and inauthentic behavior, but the arms race between manipulators optimizing for AI ingestion and platforms trying to preserve authenticity remained unresolved through 2026.