What proportion of all social-media communication is by bots, spammers, people with agendas who misrepresent themselves, or severely dysfunctional people who pass as normal online? I suspect it’s a large proportion.
There’s not much hard evidence, but every once in a while something like this turns up. I’m guessing it’s the tip of an iceberg. See also this. And who can overlook the partisan trolls who show up on this and other right-of-center blogs before elections. Where do they come from?
None of this apparently widespread Internet corruption should come as a surprise. Given the low costs and lack of barriers to entry it would be surprising if attempts to game the system were less frequent than they appear to be. Nonetheless it’s prudent to keep in mind that a lot of what appears online is probably fake and certainly misleading.