A lot of the shill marketing is very hard to prove. A lot of the dialogue gets mixed in with commentors that have genuine brand loyalty.

It's far too easy for a marketing team to acquire a high karma account and blend in. We'll never get a truly clear picture of how much Reddit is astroturfed.

This is research from before the API changes. Loads of astroturf efforts were easy to notice, there must have been more subtle ones.

I always wonder whether the famous post about vacuum cleaners was paid for by the company he recommended. If it was, they got their money's worth - that redditor was convincing.