Unless you actually have a reason to have good idea of who you're interacting with you should probably assume they are trolls, shills, or children. Those are BY FAR the most common Internet activity.
For example - I'm a normal human. I'll post a few comments on HN once in a while. Maybe a few up votes from time-to-time. Sometimes I don't think about HN for days. I don't post on other social media/forums. My father-in-law is a troll, he spends 10+ hours a day every day commenting and voting on various articles with his hundreds of sock puppet accounts. Which one are you more likely to see? Myself or my FIL?
There is an enormous vested interest to not let this become public and should make you question the concept that conspiracy can’t exist somehow
If 1 formula company has 1 reddit bot that posts 1 post every month in every parenting subreddit, is that considered a bot infestation? How many bot posts is necessary to be considered endemic?
I'd say the only real weakness is that sometimes the recommendations lean too hard on being for enthusiasts, and don't always fit what a casual user of a thing cares about. But other than that they're pretty great.
All the "just asking questions" posts pushing certain narratives in every regional subrredit are also quite noticeable.
For me that is proof enough, but other people might have different standards.