Does Reddit have an astroturfing problem? What the data suggests

The project examines whether recommendations in knife-focused Reddit communities show patterns consistent with paid astroturfing. Using a named-entity model to extract brands from comments, the author scraped 51,129 comments from six subreddits, flagged “what should I buy” threads, and identified the top 5% of authors by brand-heaviness (49 accounts). A permutation test that shuffled author labels across brand mentions 1,000 times finds the tail wrote 11.3% of buying-thread brand mentions versus an expected 7.9% (only 2 of 1,000 permutations reached that level). The excess is concentrated: r/chefknives and r/knifeclub sit well above chance while r/knives is at chance, and three specific brands (coded B003, B004, B001) show strong tail concentration (B003: 31.2% vs. 8.0% expected).

Account-level checks show some paid-account predictions hold but others do not. Tail accounts are thin in the six knife subs and tend to favor a single brand - median 12 comments in those subs and two-thirds of brand mentions to one brand - but full Reddit histories for 23 tail accounts resemble controls in age, breadth of subreddits, brand-naming and link behavior. The pattern is exactly what a few targeted campaigns or a few loud fanbases would leave, but no direct evidence ties these accounts to paid vendors or warmed single-purpose accounts.