People increasingly ask ChatGPT instead of Google. So marketers now plant fake opinions on Reddit, hoping the chatbots repeat them. Reddit is fighting back with AI of its own.

Reddit has a new spam problem, and a strange one. Brands seed the platform with stealth marketing, Bloomberg reports. They plant posts and comments that pose as genuine user opinion. The goal: get AI chatbots such as ChatGPT and Gemini to quote them as real advice.

Why Reddit is the target

OpenAI and Google both pay Reddit for its content. Chatbots lean on the site because people trust its unfiltered, human conversations. That trust makes Reddit one of the most cited sources in AI answers. It also makes it the perfect place to game.

Plant the right thread, and a chatbot might recommend your product as if a real person had vouched for it. That is the heart of a fast-growing discipline called generative engine optimisation, or GEO. Think of it as the AI-era successor to search engine optimisation.

Fighting AI with AI

Reddit now turns the same technology on the spammers. Its improved systems caught 25,000 “spammy posts and comments” a day in the first quarter, the company said. That cut user exposure by 20 per cent year on year.

Large language models now spot “the subtle, coordinated patterns of fake behaviour and artificial hype” that older tools missed. Reddit also checks new accounts for warning signs before they can post.

Humans still do much of the work. Community moderators handled more than half of all removals in the second half of 2025, Reddit disclosed.

A cat-and-mouse game

Marketers refuse to give up. Shanzila Ahmed runs the agency ReachLLM. She said she has landed client posts in ChatGPT within a day, though Reddit later removed some of them. Her workaround captures the whole contest. “We just need to keep pushing out good new content at regular intervals,” she said. Investors smell opportunity too.

The GEO startup Profound topped a $1bn valuation this year. It joins a new breed of firms built to make brands visible to AI.