lammert - 11:29 am on Dec 12, 2011 (gmt 0)
I am using a remote proxy regularly because of the lousy network I am normally on and the proxy I use is configured to forward no IP address information from the client side to the outside world. The same can hold for VPN configurations.
The IP address of the client cannot be tracked in such a situations but I have encountered sites which blocked me anyway because the IP address of the proxy was located in a data center, rather than on a residential address. I guess this had to do with scraper blocking though, rather than blocking individual visitors from a specific set of countries.