[6ren]

Your edit is much clearer than "you know it when you see it" (Justice Stewart), which pretty much represents giving up on any formal definition.

I like your suggestion of detecting trolls by whether they actually transmitted/helped anyone with the invention. There's a problem in patent law, that you're infringing even if independently invented it. (Copyright is different, you only infringe if you actually copied - though see "unconscious copying"). Your suggestion could be implemented, I think, just by getting rid of that. Which might be a good thing, though difficult. It's a big change (though copyright case law and legislation would provide some guidance.)

Of course, inventors need to be able sue people that they didn't help produce it, so the copying part is important.

Alternatively, make it a requirement that you have to make prototypes and put it into production. This is also a big change (though, in the past, a prototype was a requirement). But I think it would be easily gamed, with shell production companies. From the other side, for real inventors, what if production requires substantial capital investment? The producer just refuses, and the patent fails. Maybe other requirements could avoid this, but seems tricky.