It's unfortunate that they are doing this. There is a captcha upon registration to try to prevent automated bots from registering. New members are also required to verify their email address before they are allowed to post.
Despite those efforts, a few spam threads do make it through daily. Aside from a stronger captcha in possible future forum upgrades I think deleting them and banning the user as soon as they are seen is the best way, which is what we've been doing. Having new threads appear on IRC helps this as well so we see them sooner.
If there are any threads we miss, anyone please feel free to report them and they will be promptly removed.
-Mark