I'd like to propose a general rule:

If you have anything useful on the Internet, sooner or later spammers will try to ruin it.

Today's example? del.icio.us.

For those who don't know, del.icio.us is a nicely-executed social bookmarking site — perhaps the social bookmarking site. It's not 'social' in the way something like Friendster or a bulletin board is social, but the fact of having a large number of people working in a shared space gives you something that you don't get when everyone's off in their own little corner: specifically, the possibility to stumble on things that other people have found useful or interesting and which you might not have discovered otherwise. del.icio.us does this well, and it's deservedly popular.

Naturally, spammers want a piece of that action. In fact, one of the surprising things about del.icio.us is how spam-free it is, especially when you consider how open it is and how rewarding it could be to exploit. I've been using del.icio.us for a while now, and I've only just seen my first piece of del.icio.us spam.

Spamming del.icio.us is simple. You pick some popular keywords and use them to tag whatever link you want to drive users to, then add a description that you hope will bring them to your page. So, for example, a del.icio.us user named 'franceromance' has tagged a batch of links to a porn gateway (hosted on blogspot.com, whose free services are also heavily abused by spammers) with keywords that include 'photoshop', 'design', 'webdesign', 'rails', 'productivity' and a few other popular topics. To make sure that these do show up in the listing for the 'webdesign' topic, the spammer has created another couple of accounts — 'SimicBasilisk' and 'UsefullLinks' — and used them to tag the links with the same keywords. del.icio.us dutifully reports that the link has been tagged by "... 2 other people", and the webdesign listings start filling up with spam.

The threat to a service like del.icio.us is significant: a spam attack that introduces junk into del.icio.us's indexes will degrade the usefulness of the service for everyone. del.icio.us is now in the same position as Google, forced to constantly patrol and protect its data in order to prevent spammers from making it worthless. The fact that I haven't seen much spam to date suggests that they're generally successful and with Yahoo!'s experience and technological muscle behind them they may be able to keep their heads above water. Nevertheless, the threat is there: the service is popular and useful, therefore the spammers will try to destroy it.

The spammer's intent, of course, is not to destroy anything. The spammer would rather see del.icio.us healthy and functional, so that the real, useful content on the site will keep bringing in new potential viewers for the spammer's links. But unlike biological parasites, which are finely-tuned by evolution to avoid destroying their host while it is still useful to them, spammers — as a group — don't know how to stop. Their use of services like del.icio.us may be parasitic but in practice they behave more like cancer cells, which multiply uncontrollably until the host organism dies.

Unlike cancer cells, spammers can desert a dead host. Use to destruction and move on is a workable strategy, at least in the short-term, and spammers are nothing but short-term thinkers. In the long-term, spammer vandalism will eventually hurt the spammers themselves. When an application stops being useful to real users due to abuse, it also stops being useful to spammers. Unfortunately, it's not much satisfaction to know that when the spammers have trashed the neighborhood sufficiently, even they have to move out.

Abuse of valuable applications seems to be inevitable, but complete destruction may not be. Google has done a good job, by and large, of maintaining a useful service in the face of continuous assaults. The cost in terms of man-hours and resources is probably significant, however, while the cost in terms of opportunities foregone — all the amazing things we could do if we didn't have to fight off spammers and vandals — is probably incalculable.

The worst aspect of spammers is that they're ready to make everyone else poorer if it will earn them a few bucks.