Fake Reddit Posts Are Hijacking What AI Tells You

In late May, moderators of r/Biohackers, a Reddit community with roughly 830,000 members, restricted new standalone posts about peptides and hormone replacement therapy.

The subject matter was not the issue, 404 Media reported June 3. Peptide and HRT companies had been flooding the community with coordinated promotional posts designed to be scraped by artificial intelligence systems and surfaced as answers in ChatGPT, Google’s AI Overviews and other AI search tools.

The tactic has a name: answer engine optimization, or AEO. Where traditional SEO aimed to rank pages in Google’s index, AEO targets the source material AI systems pull from when constructing answers. The goal is not a link users click. It is a sentence an AI speaks.

Reddit sits near the top of that source pool. Between August 2024 and June 2025, Reddit was the most cited domain by Google AI Overviews and Perplexity and the second-most cited by ChatGPT, analytics platform Profound found in June 2025. Google’s AI Overviews cite Reddit in 21% of responses, analytics firm Demandsage revealed in December.

That reach is what makes the platform a target.

The Tactics Are Getting Harder to Catch

The campaigns are not crude spam. Operators use accounts with established posting histories designed to look like ordinary users, TechSpot reported June 4. In some cases, real people are paid to post, blurring the line between genuine discussion and coordinated promotion.

“You literally just sort of know what to look for,” one moderator said, per the report. “But the problem is you don’t want to become punitive to the people who aren’t doing this maliciously.”

Marketing firms are selling AEO services openly. The top 100 tracked subreddits account for about 84% of recent brand mentions in AI-generated answers, Startup Fortune reported June 3. A campaign does not need to be broad. Seeding a small number of high-traffic communities can reliably shift what AI systems say about a product. The commercial logic is straightforward. If a brand can place its messaging inside the threads AI cites most, it controls the answer without buying an ad.

Healthcare and Commerce Are Most Exposed

The r/Biohackers case puts the stakes in plain terms. The concern is not abstract marketing ethics but physical harm, the moderator told TechSpot, per the report. Peptides span a range of injectable compounds from GLP-1s to less-regulated substances advertised for muscle growth and anti-aging. A consumer asking an AI assistant about dosing or vendor legitimacy may receive an answer shaped by the vendor itself.

The exposure runs wider than healthcare. The PYMNTS Intelligence report “The AI On-Ramp: Data Shows How Everyday Tasks Build Consumer Habits” found that 31.4% of AI users turned to generative AI to find product links in February

The PYMNTS Intelligence report “How AI Becomes the Place Consumers Start Everything” revealed that more than 60% of consumers now start daily tasks, including shopping, inside AI platforms. Financial services and eCommerce face the same exposure as healthcare, including any category where consumers turn to AI for recommendations rather than doing their own research.

Traditional SEO spam was visible. Users could scan links and assess sources. AEO leaves no trace. The AI answer arrives as a synthesis, and the promotional post that shaped it never appears.

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