I was one of the people that had a very bad experience with SORBS.
My company got a new ISP with an external block. I'm sure at some point that block had been used as a dynamic range. I had not set a PTR record (because the IP of the mail server changed at the last second), my PTR and A record for that mail server were not set to 12 hours (seriously, who does that?), and I was banned on the SORBS list. I had an SPF record, you could obviously see that I'm part of a legitimate organization, and it would have taken maybe 2 minutes of work for an physical admin to realize that this was a mistake.
It took two support tickets with SORBS, 5 calls to my ISP, and around 10 days to get off the list. In the meantime, we could not contact certain people using it. And what's worse is that the only solution that the admin of SORBS had was to get everyone to stop using the SORBS list. I think that the TTL requirements are the worst part of their solution.
In my opinion, an unattended, automated black list is worse than the problem of too much spam. You are blocking valid mails, and because you are blocking it at the IP level, the end user doesn't even see it show up in their spam bucket many times. If SORBS had a single admin, checking their email once a day, they could easily filter out some of these issues.
I encouraged several anti-spam vendors to stop using their services for this reason, through the different companies that we interact with. There are several other blacklists that do their job well, there is no need to use an unattended blacklist.