Killfiles are the generally accepted way of combating spam on Usenet. With only a few lines, I see very little of it even on the wider Usenet groups.
Generally blocking public services (like Google Groups) is enough to block 90%+ spam
Generally blocking public services (like Google Groups) is enough to block 90%+ spam
That said, one of the things I really liked about Usenet is that the client was entirely in your hands. Some of the Usenet readers were incredibly sophisticated and no internet forum software has ever come close to offering an equivalent level of utility. I would jump on a "Usenet, but with moderation/spam control baked in" in a heartbeat. In fact this is pretty much what Reddit is, which makes me sad that they're trying so hard to Digg it.
And blocking public servers would kill the network effects. Thus keeping it only to small communities.
I have and enjoy using “public” Usenet servers like eternal-september and SDF which disallow spam and hold users accountable for their actions.