I think scam generally implies that someone was swindled, told they'd get A and get Q (or nothing at all). Sold a bill of goods (but not the goods).
In the case of something like Reddit, you come to read content, and once you've readit, you write it, and then read some more. I'm not sure you're ever really sold that you're even engaging with actual people.
These days, I frequently wonder what percentage of comments on any of these sites is genuine (although I happen to believe it's still a pretty high percentage). Its good to assume noble intent, but to also carry around skepticism.
