what counts as a "troll" case
In general, "patent troll" refers to NPEs - Non Practicing Entities - companies that don't produce/manufacture/sell anything (except patent licences).Most companies avoid patent litigation in all but the most severe instances, because so many people hold patents for the most obvious of things that they might well get counter-sued by the company they're suing. Mutually Assured Destruction in patent form.
NPEs don't have this concern, so they can send out all sorts of dubious claims without fear of countersuit.
An alliance against NPEs (with a rule preventing NPEs from joining) might well be worthwhile.