From what I'm seeing, this isn't just an issue that we're facing, but a concerted effort since January that is hitting a ton of locations, and we are currently working on them with other like-minded online communities. It's not a code issue; it's an asshole spammer issue. We've taken steps and will continue to take steps until we find the right amount of effort to curb this without turning it into a complete slog for our staff and moderators.
We absolutely could crack down 100%, put all new members on moderation, and turn the process of registering and joining the forums into a complete and utter slog - but that'll frankly just alienate those making an effort to join properly without alternative issues. We've changed up a few things in the last couple of days; we'll see how that pans out.