I’m deeply mystified by the hallelujahs bursting forth about Google’s rel="nofollow" method of preventing comment spam. The idea being that comment spammers will leave your own site alone, or stop spamming altogether, if they find the rel="nofollow" tag.

I think this is false assumption. It’s based on the idea that producing a link costs something, and therefore the spammer must choose either way. Think of it this way: if I’m a guy trying to pitch a TexasHold’em site, my aim is to get people to go there. Whether this is directly, through a click through, or indirectly via Google, the effect is the same. As a spammer, I don’t care at all *how* they get to my site. I just want the eyeballs. The same for any of the other comment spam subjects. PageRank isn’t an end in itself, it’s just the means by which they get more readers indirectly.

So as comment spam costs absolutely nothing to spread, there’s no loss to me if I spam sites with rel="nofollow". It might be, at a pinch, less efficient a method of getting readership, but it will still work: and efficiency is not a factor at all. Spamming costs nothing, so spamming sites with rel="nofollow" doesn’t bother me. I’m not losing. Perhaps I’m not winning as big, but I’m not loosing anything either. There’s no incentive for me to spam those sites for the sake of getting Pagerank, that is true, but there’s even less incentive for me *not*to*. Why would I bother even testing the site for rel="nofollow"? I might as well just hit it and leave. It’s less work for me, for exactly the same gain (some) and exactly the same loss (none).

The same effect occurs with sanitized comments. So people can’t click through from that site. So what? I’ve lost a microsecond of processor time and a few million electrons? Ho hum. Onto the next million URLs. Spamming costs *nothing*, so if it doesn’t work 99.9999999% of the time, so what? The remaining successes are still worth something. So I’ll just keep doing it.

This is the key point. If rel="nofollow" works, if it’s applied universally, it will actually have the reverse effect. It actually gets less effective the more it is implemented. Why? Because the comment spamming sites are in competition with *each*other*, and not with any legitimate businesses. They’re not so much trying to get the best pagerank for their term, as trying to get a better one than their rivals. That’s a key distinction. If the playing field is levelled by rel="nofollow", then everyone involved will be forced to try all the harder to get their links out there. The blogosphere will be hit all the harder because of the need to maximise the gains. As there’s no more effort in hitting 6 million blogs as there is in hitting 1 million, this really won’t bother the spammers one bit. All it does is shift the problem from the high pagerank blogs we here might have, with rel="nofollow", custom sanitize settings, and mt-blacklist in full effect, all the way over to the less technically adept. And that is one enormous customer service problem heading towards Blogger, 6A and the rest.

Just as email spam to me is a dull throb in the background mashed by layers of bayesian widgets, but to my AOL using mother-in-law is a show-stopping internet-repelling turn-off-the-machine torrent, forcing comment spammers to cast a wider net will cause them to target the long tail of people who have no idea what to do but come screaming at tech support, or slagging blogs off to their friends.

That would be a disaster.

Meanwhile, Scoble points out how it can be used in other ways, and undermines the second aspect of the attribute: as respecting rel="nofollow" will involve losing an enormous amount of implicit metadata, any tools that are interested in that will be forced to ignore it. Technorati will have to choose if it’s a site that measures raw interconnectivity, or some curious High School metric of look-at-that-person-but-don’t-pay-her-any-attention that the selective use of the rel="nofollow" attribute will produce. For many purposes, this would mean the results are totally debased and close to useless.