One of the difficult things of trying to share ideas, or teach a concept to large group of people is the different levels everyone is at. What some people consider advanced others consider intermediate. The second problem is the larger and more diverse the audience, the more general and ambiguous the examples have to be.
Ask any advanced SEO to describe what they want in a link and you’re likely to get something like this …
“A keyword rich link from a well linked/important/popular page on a trusted and authoritative website, that is preferably topically relevant to your site”
The problem is that a definition like that has so many loosely defined concepts it’s borderline irrelevant to someone who doesn’t have some level of experience. The most ambiguously defined part of that statement is “trusted and authoritative website”, because there’s no real publicly available/agreed upon metric for trust and authority.
Enter the page rank conundrum. If I were to tell you I need you to work on getting me at least a dozen links from trusted websites in the next 30 days, how can you be sure you met my definition for trust? If I was to tell you get me a dozen links from websites with a page rank 4 or higher, it’s a much more clearly defined goal.
However page rank is no longer an accurate measurement of anything. Since google has admitted that they will adjust/manipulate page rank of sites they believe are selling links, and those adjustments will trickle down/out, page rank is really just for entertainment purposes.
We’re back to the problem of not being able to give a quick and easy metric to teach/show people what’s a trusted/authoritative website, and there’s no way for them to asses accurately. Lots of experts, myself included, use the NY Times or the Wall Street Journal as an example of trusted websites. While it’s true they are trusted, it’s a cop out answer. Since the only way you are going to get into those papers is do something newsworthy (like run over your neighbor with your parakeet behind the wheel of your hummer), or have a high paid PR person on your payroll, they are relatively unattainable.
The only real answer is research and gaining experience. Use lots of other metrics, alexa, compete, technorati, quantcast, hitwise, feed burner and page rank. Look for numbers/statistics that line up and correlate. Look at the blogs in that space, see who is getting the most citations/links. Getting a good grasp of the space is not something you can do accurately just by looking at the little green pixels in your tool bar, but until one comes up people will continue to use it as crutch, because it’s quick and easy, and nature abhors a vacuum.