I have tried to sign up for a few services/accounts, most recently on http://forums.debian.net and was pretty much denied with messages like:
IP Address 126.96.36.199 is listed in the CBL. It appears to be infected with a spam sending trojan, proxy or some other form of botnet. It was last detected at 2014-03-26 07:00 GMT (+/- 30 minutes), approximately 5 hours ago. This IP address is infected with, or is NATting for a machine infected with the ZeuS trojan, also known as "Zbot" and "WSNPoem".
I got similar messages for each of the 4 times I tried a new identify and tried to re-sign up. This is a bit frusterating and I was wondering if there is some way around this without compromising my anonymity?