Aaron had a brilliant post yesterday on on Bad Advice that Sounds Good. He noted a few "white lies" of the SEO world that we continue to perpetuate. I agree with some of them wholeheartedly:

Create quality content. Why do I hate it? If you don't have much brand recognition higher quallity content will lose out to average content. Most people never talk about the social aspects of the web when saying to create quality content.

Create your website for users, not for search engines. Why do I hate it? Search is marginalizing many publishing business models. To pay for the costs of creating linkworthy content it makes sense to add a significant amount of lower cost highly monetized filler to a website.

I also want to add a few that I've found:

• Anybody can be a blogger
  It's just not true - you have to be able to connect with an audience, write consistently interesting material, dedicate time in the beginning to the craft, despite the fact that no one's reading and find ways to make yourself stand out from the hundreds or thousands of other bloggers in your field.
• Don't plagiarize
  Obviously, I wouldn't recommend that you steal content, but being succesful on the web is often about re-purposing ideas for content, technology, value, capitalization, branding, advertising and everything else that falls under the umbrella of web marketing. Steal an idea, improve it and make it appeal to an audience likely to link to it - you don't have to work hard, just smart.
• Making money in SEO is easy
  Yeah, the salaries are fairly good in the established tech hubs of the US, and the consulting gigs can be very lucrative provided you have a reputation. For basement-SEO-types, affiliate revenue is still strong and MFA sites can earn a return, but all of this requires deep knowledge, insight and the will to work through the ugly times to get ahead. It seems like a cakewalk because there are some very smart, somewhat lazy folks making a great living, but to compete with them, you need the years of experience + trial and error to know where to expend the minimum effort for maximum return.

I have little doubt that SEOmoz has given out some bad advice over the years, either directly or through unclear references and it will always be something we have to work on.