For a long time it was trivially easy to spot the ads and shills, especially on reddit. It's definitely getting harder and LLMs are going to make it even worse.

But this is kind of why I don't understand the butthurt reddit is having over third party apps. They are clearly pushing for a much more guerilla model for marketing which doesn't rely on traditional ads. If they can actually make that work, the ability to push impressions through the API would make them very rich.