A lot of times, vendors don't realize that it's so frowned upon over here. A friendly warning in their thread might put them on the right path. I'd hate to see good vendors get clubbed due to ignorance.
Rather than creating a rule, this could be a great chance to post in the vendor's thread "Stop bumping your thread. We don't like it around these parts. If you keep doing it, you'll get banned (
proof). It's your choice. The warnings don't get friendlier."
About the review beggars:
Maybe someone could go into the vendor's thread when the beggar shows up and say "If you're gonna give a free copy to plusmin, do it as spec work, not for the review. Nobody around here respects his reviews or itraders (
proof). It's kind of a black mark. Unless you think it's gonna turn into future work from him, I wouldn't do it. You'd just be spinning your wheels for nothing."
Measured community involvement is key to making this work. It'll get messy at times. None of us are perfect. We're gonna hit false positives, and let a few idiots slip through the net. That's gonna happen.
But we'll figure it out as we go, right?