Opportunity Cost
Over the last year, Google has gotten much better at detecting link exchanges and giving them no weight or negative weight. Typically for most savvy webmasters, the effort, time and money wasted on a abundant link exchange program would be better spent in providing quality backlinks(dofollow) linking to your website, original, link-worthy content. Trading links with a couple exceptionally relevant related resources might be a good idea, but don’t waste your time trading dozens or hundreds of links.
Does it Work?
Not as well as it once did. Many people who created SEO software, or information products that sold themselves as experts, found that their Google rankings tanked hard core because link exchanges are not all they were once cracked up to be. If you go too far off topic with your link exchanges, at best it is an opportunity cost waste that will have limited upside on your Google rankings. At worst, it can waste your time and put you in spammy web communities that actually cause your site to rank far worse than it would if you stayed away from the spammy link networks.
