As of right now, there is a popular host in Garry's Mod that uses Anycast technology for their (D)DoS protection. While this technology is acceptable, it is allowing servers to (in my opinion) cheat the Valve Master Server and result with more exposure to the public. Read this thread for more information on how this is done.
Many of the top servers in Garry's Mod are using this host along with the Anycast technology. This gives them a big advantage over servers not using technologies like Anycast.
I'm confident Valve could patch this within their Master Server. However, unfortunately Valve doesn't appear to care about this issue (what a surprise). I am also sure FacePunch could blacklist servers that do this. But it technically may not be the server owner's fault because the host is using Anycast (which is proper (D)DoS protection as well).
Regardless, I plan on sending emails to Valve along with FacePunch to discuss this issue further and see if it can be patched. It is indeed unfair to servers not using Anycast. I also plan on learning more on how Anycast works and so on.
Edited by Roy