Though I by no means consider myself an SEO "expert" (is there such a thing?), I try always to take a pragmatist-positivist approach to SEO techniques. That is, I research a technique, try it out on a personal site, observe the results, record the data, repeat the experiment, then publish the findings.

Unfortunately for our industry, many SEO "specialists" have got this the other way around. They first publish their hypotheses as SEO Law, without doing any hard experimentation, record no data, observe no results, and do no research.  

So, I was surfing the Web one day, and I found this blog post about the various types of meta-tags. The writer made some pretty daring claims about the efficacy of infrequently used meta tags such as the meta-classification, -subject, -abstract, and even the meta-pagerank tag. (I know, I thought the same thing: does such a tag even exist??) The author claimed that, by utilizing these tags, he experienced significant ranking increases among the major SEs. 

I tried them out myself. I sprinkled these various meta tags on various pages of one of my sites, and then waited. 

And waited.

...And waited.

Then, I waited some more.

Nothing. Not one single significant change in SERP, PageRank, or spider traffic.

The moral of the story: Be wary of self-proclaimed SEO "experts!"

The famous English poet Herbert Spencer once said,

"There is a principle which keeps a person in everlasting ignorance, which is a bar against all knowledge, and an obstacle to all sound argument; that principle is the principle of contempt prior to investigation."

If Spencer were writing for today's SEO industry, Spencer might have framed it thus:

 "There is a principle which keeps an SEO specialist without any clients, which is a bar against all SERP promotion, and an obstacle to all sound SEO practice; that principle is the principle of publication prior to experimentation!"