I happpened across this post today about de.licio.us and their effort to combat spam when  I saw this comment by Randfish that I found interesting...

....The cloaking prevents both unauthorized agents (though anyone "unauthorized" is also likely to ignore robot commands) and discourages potential spammers from tossing their links on the site.
Emphasis added by me...

Now, when you're spamming, as far as I see it, you've got a couple of options.  The first is to go for quality targeted backlinks.  This is usually very difficult for most folks because they don't know where to find those tasty high PR links.

As a result, the majority of spammers end up using the high volume approach.  They'll throw up tons (billions in some cases) of pages and go for as many links as possible.  They'll use bots to search the net looking for places they can insert their links into and typically will use custom scripts to exploit popular tag sites, blog sites, etc.

So what's the big deal with the comment above?

Well, most of the spammers who are going for the volume approach are not going to even bother looking to see if their links are getting blocked or not.  To be sure, some will notice, but for the most part, they'll simply scrape like mad looking for what they want and pinging/commenting/posting away to get those backlinks.

Witness the number of spams in guestbooks that put nofollow in their backlinks or the number of spams that are blocked by akimet<sp>.  Throw enough crap against the wall and some of it will stick...

Interestingly enough, I'm in the process of moving away from the bulk process myself.  I'm sure some are going to wonder why and, to be quite honest, I'm really not sure.  Perhaps I'm tired of the treadmill that it's become.  Perhaps it's something else.  There are some other things that are appealing to me at the moment so for the time being, Google et. al are safe from my billions of pages of spam.

Now if I can just figure out this PPC arbitrage game.  I think it's got some bang for the buck left in it ;)

G-Man