by ailurophobe » 05 Jul 2010 21:17
Connecting to P2P thru a proxy or ISP NAT is fortunately rare. NATs are probably common enough to be an issue if you start blocking them, but I doubt ISPs like people spreading spam and trojans from their NAT any more than we do. Less probably.
The bad news (as you know) is that the GUIDS, being trivial to change, are not useful for blocking, they can however be used for credit systems. They are currently only used for anti-leech, but they could be used to add a reputation system to ranking search results as well. A reputation system would also allow negative rep to results from the same subnet as a known spammer without the problems hard blocks cause.