Sometimes it is ok for me to remove dated or less appropriate comments when updating or revising articles, in fact that even happened automatically in some cases when rechanneling a certain way. Still unblacklisted people whose one or 2 things do not even apply anymore because the article was updated (contents or pics) do have constant new chances of commenting, which is not bad in general. And I still need their "negative" feedback for improvements.
The individual I BLed is still commenting anonymously, I think. He is not endangering my thread, just making other peoples a bit longer. But he is less active and may have had to change hashes. BLing and viewing audience changing will never be perfect in my system, because I do want unregistered people in some sites. You could BL their hash even when they are anonymous. Sometimes that helps. Even some rather good people I know of have to cheat on hashes for monetary reasons. When they are grown up, you could treat em a bit differently. Yet when do grownups earn enough money? Some earn enough when minors, not all are rich when turning 18. For normal blacklisting decisions not related to software registration cheating but negative comment input, you do not have to mind about age anyway.
I will not be worried about a virtual train wreck as long as I am almost positive they are still active anonymously. Temporary BL seems best in general. But for me, that could take much longer than a couple of months in some cases. The damage some caused is my now always checking how long a site exists around here before making many comments or ratings. And my own sites are not old at all. Crazy.
But in big site complexes, I am willing to pay a price for the valuable experiences and more you get, at least here. There are so many good people specialized in so many good things (cars, religions, software, politics, cooking, humor, skinning...). And the viewpoints are coming from various parties in Australia, the U. K., Norway, the U. S., Israel, Germany, Canada just mentioning what I found in two months.
The longer I am into these things, the faster I know when I can afford to blacklist. If you can afford to run and think about one site only, your blacklist decision is harder, but you have more time for it. Stardock rejected my skins. No problem. They download fine elsewhere. Not all of them, but this was important and no subscrip was paid for, either. BLAM! Another site. The more sites I have to run at once (currently 4 in the very beginning, plus external posts), the less time I have to think twice about how to keep things running (again/temporarily, at least). Luckily the types we have in my mind are still exceptions around here (20 bls would not be much, 1000 private subdomains are in the first list I checked here, so that is a 1 : 50 ratio. Sounds bad in a small surrounding. Here that means you have 980 left over. Good enough for many, many purposes or just fun and relaxation, distraction.