From the spammers' perspective, it's a "tragedy of the commons" situation. To each individual spammer, it is worthwhile to keep posting on craigslist for the sh

From the spammers' perspective, it's a "tragedy of the commons" situation. To each individual spammer, it is worthwhile to keep posting on craigslist for the short-term even if the sum of their actions is suboptimal in the long-term.