I've seen the ugly side of blacklists in the past three years. On twitter, I'm on two different blacklists, and named one of the worst harassers of the internet. All of this is a bold faced lie, obviously, and my twitter archives can prove my innocence. My crime? I followed people I thought were interesting. People who evidently pissed off certain people with a whole lot of power. Then again, the creator of one of the blacklists received a C&D from the FreeBSD foundation because she was having a negative impact on their public image. (It's a long story...)
My only admonishment is to be 100% certain that the person you're adding to the blacklist is worth putting on that list. Keep evidence on hand in case anyone asks questions, and make sure it's something you can prove beyond a reasonable doubt. A judicious approach will always lead to a much better outcome. It doesn't matter if it's popular as long as it's done right.