Ghost in the open source machine

One problem open source advocates seldom acknowledge is the disrespect many people have toward what's held in common.

You see it in the world with "street spammers" nailing ads to trees in public parks. You see it online, in the attitude spammers take when caught.

Lately I've seen my RSS feeds becoming heavily polluted by RSS spam -- entries that are just ads, or sets of links that all lead to purchases (on which the spammer gets a cut). Maybe it's because I've been covering cellular technology a lot. (I'd love to hear your experience.)

The RSS specification is run under a Creative Commons license, which BoingBoing defines as "open source for things other than code."You must attribute RSS to its creator, and distribute improvements under the same license.

Question is, who polices what no one owns? How can we maintain the cleanliness of the commons against those who don't share its ethics? It's a question that has haunted the Internet for 10 years now. It's a question that, frankly, haunts every open source technology.

It's the ghost in the open source machine.

UPDATE: We've gotten a lot of comments, which is good. But some may misunderstand the point here. I'm not criticizing open source, or RSS. The question is, how does the commons enforce its ethics on the unethical?