As a blogger I can’t tell you how many spammy link requests from “link builders” that I get on an ongoing basis. It’s just way too many. You certainly don’t want to hire the kind of link building firm that sends out such spam link requests using cheap third-world labor. It’s these same sorts of firms responsible for a big percentage of the useless keyword-rich link-containing comments posted all over the blogosphere.

On one end of the link builder spectrum you have the solo operator guru, somebody of the caliber of Eric Ward, to the other end of the spectrum — those link building sweatshops out of India that will spam the hell out of the blogosphere and of webmasters’ email inboxes on your behalf. You’ll want to hire a consultant or firm more towards the former rather than the latter (obviously). At least if you wish to be working with a top-notch link building outsource partner, one that’s really going to “do the business” for you, and not spam in the process.

A good SEO firm should also be a good link building firm but this is not always the case. In fact, it is not often the case. On-page SEO and technical tweaks like rewrites and redirects are a very different animal from the outside-the-box thinking and unbridled creativity required for link building, and link baiting in particular.

A great example of such creativity is the business cards for life contest that we at Netconcepts dreamed up for our client Overnight Prints that involved the Internet celebrity and Technorati Top 100 blogger Jeremy Schoemaker. The contest was to design Jeremy’s business card, with Jeremy serving as the ultimate judge. (Here’s the winning entry, btw. It’s one sweet business card.)

Another great example (not sure which consultancy is behind this one) is A&E’s “Hammer Pants” flash mob stunt:

What are some things to look for when hiring a link building consultant or agency? Here are a few:

• examples of creative, out-of-the-box thinking (as already explained above)
• demonstrable success with link bait being well-received by social news and social bookmarking communities
• the tools necessary to do the job well (e.g. LinkScape, Raven, BuzzStream, SQUID, Enquisite, Internet Marketing Ninjas, SEO Book tools like the Hub Finder, etc.)
• happy customer references
• a good reputation in the industry (as judged by mentions on SEO blogs, forums etc.)
• ideally, evidence of thought leadership (e.g. conference speaking, magazine articles, quotes in mainstream media, a great blog…)

Plus I asked the link mensch himself, Eric Ward, to chime in with some more pointers, which he did. According to Eric, you should ensure that you…

• are given a rationale as to why they want to pursue any given target
• have final approval on every target site they contact
• have final approval before you agree to link back or pay for a link
• are provided a stated deliverable and you have agreed to it
• get an expert to review the contract, like me or Stephan. (Paying a few hundred bucks for a deliverable review might be the wisest money you can spend.)
• are given at least monthly reports of progress

In my most recent Search Engine Land article I wrote about tracking ROI and cost-justifying link building initiatives. It may be helpful to incorporate such metrics into an engagement.

Remember that this is much more like hiring a PR firm than an ad agency. PR firms (and link builders) can influence — but not control — outcomes. Ad agencies can control the number of brand impressions just by simply spending more dollars.

Good luck!