Hacktoberfest is upon us, for better or worse, and to pander my ever-inflating ego, I think I've got the answer why my repos don't ever see any activity on them: they don't have any tags on them (apart from Webscreen) and they're written in what could be considered obscure languages. Most repos that appear to get bad faith PRs are either popular on their own, or are in a popular language (which is to say Python or maybe Node).
Either way, if any of my repos get even a spam contribution, that would be kinda nice. But I can't say I want to be noticed. I'm fine doing the stuff I already do, with little regard for the rest of the world.