I think it may be time for a new acronym for the idea of optimizing your site for Search Engines. The current term "SEO" has a problem because while it's clear to everyone what the goal is (a higher rank in search engine results), it's vague about how to achieve that goal. As a result SEO has been broken into two different categories:
"White Hat SEO" - Generally meaning anything done to modify a website to make it more readable and searchable by Search Engines.
"Black Hat SEO" - Pretty much anything and everything else done to improve search result positioning.
Why should you avoid Black Hat SEO? Well, the goal of any search engine is to provide results that are userful to their users. If you somehow manage to convince a search engine that your site is useful for a set of search terms when it actually isn't, your are essentially taking advantage of flaws in a search engine's algorithm. As search engines continually refine their algorithms to get rid of sites like yours, at some point your site will fall back down the results list. If you did the hacks yourself, not a big deal, but if you paid $5000 to a SEO Company to get you a #1 Ranking for motivational office wall-art and are now on page 10, you are SOL. Even worse, Search engines maintain blacklists of sites that try to game the system and so you may not even show up on page 10.
What's option B? First, make sure your site isn't just a 1-off get rich quick scheme. If it is, see option A. That's your best bet, milk it for as long as you can then go take advantage of people in another god-aweful pyramid scheme. If your website is actually has a worthwhile niche that you think should be at the top of search results, you need to sit down and figure out with your web developer the best way optimize your site's content in a way that actually provides value to it's viewers. As such I propose that term SEO has been misused and bastardized that it is no longer really a good term to describe the many subtle varients of the business. Here are my favorite replacements for the White/Black Hat SEO's:
"SEA" - Search Engine Accomodation - Accomodating search engine spiders by making it as easy as possible to succesfully find and index the content of you site.
"SEM" - Seach Engine Maniuplation - Taking advantage of flaws in a search engines to try to gain a temporary boost in ranking.
The next time you're talking to someone trying to sell you a SEO package, ask them what their strategy is to give your site a boost.