Google wants websites to use nofollow tags to clamp down on spam comments and spam entries in guestbooks. But they don’t want sites to use nofollow tags to direct their “link juice” toward new or struggling internal pages of their own sites. And Google has convinced some of the hot sites right now (like Twitter) to make all the links from people’s bio pages nofollow, even if that person has Tweeted his or her heart out to build a real following with real content. As you might surmise, there are lots of Twitterers who resent this.

Google has not yet figured out a way of teasing out the sites that are using paid content to hedge their search engine bets for obscure searches, but I’m sure they’d like to figure out a way to do so. Google’s steady drum-beat is “content is king,” and though adaptations like the nofollow tag may have their usefulness in squashing comment spam, Google really can’t blame webmasters for learning to use these adaptive tools to help their own sites.

We’re always saying, basically, “link farms: bad.” And that’s true. Links swapped for the sake of getting links with no consideration of quality or relevance is the unprotected sex of the SEO universe. You do it at your own (considerable) risk. There are, however, a few sites that people join in order to find other sites like theirs that they can evaluate and exchange links with. Google’s Webmaster Guidelines basically say that this is OK as long as you don’t do it “excessively” (see screen shot).

What’s the definition of “excessive”? Ask yourself if you’d be asking for the link were there no such thing as Google. If Google didn’t exist, and you still would have deemed a link with the site to be a positive thing, then go ahead. Otherwise don’t. The problem with even the good link exchange sites is that usually the link juice you’d get from just one high quality site that you approached independently would probably trump five or six links from the other sites participating in the link exchange. So while targeted link exchange sites aren’t necessarily going to ruin your site’s ranking, they’re probably not going to help all that much either.