I don’t have the time to explain to you how much SORBS sucks and how I wish that their servers and their whole organisation would just disappear from the face of the internet, so I’ll point you at some other reports:
One of the GMail MTAs (qmail.gmail.com) has been listed in the SORBS database (due to one jackass sending a mail to a SORBS spamtrap address) and now I haven’t been able to send mail to a number of my friends and family. Many GMail users will be terribly inconvenienced by this. If I want to have the IP delisted, I’m supposed to pay SORBS $50. That’s extortion!