Well, as long as you’re following the guidelines set forth by the search engines themselves, why on earth wouldn’t you want to optimize a site to appear high in search results for relevant queries? It’s only logical, and it only makes tons of sense, particularly for online businesses, or those hoping to earn money in some way from their web presence.

Then, there’s blackhat SEO. And that’s a whole other thing. A whole other bad thing. Just as there are unscrupulous plumbers, auto mechanics, landlords, and practitioners from virtually every other industry, there are also, unfortunately, unscrupulous SEOs who fly in the face of Google’s well-known “don’t be evil” motto.

So in the spirit of caveat emptor, you should know what you’re actively not looking for when seeking a search practitioner. We’ve already looked at a few obvious red flags. You’d never hire an SEO who you met via a piece of spam in your e-mail inbox, nor hire someone who made outlandish promises, such as a number-one position on Google.

In fact, run, don’t walk, away from any SEO who promises guaranteed rankings on competitive keywords or phrases. Anyone can get you to rank highly on a wildly obscure phrase no one would ever search—but why would you pay them to do that?

A whitehat SEO will be more than willing to explain clearly how he intends to help your site to rank in search engine results, while at the same time ensuring that the site is designed primarily for the end user. That means no deceptive or misleading text. It also means no doorway pages, a frequent blackhat SEO tactic.

Doorway pages (also sometimes called jump pages, gateway pages, or entry pages) are pages designed to show up in search results, but to essentially never be seen by an end user. When that page shows up in search results and a user clicks, they’re immediately redirected to the client’s web page. Aside from violating the search engines’ own guidelines, it’s also important to remember that you don’t control the doorway page; the unethical SEO does. Tomorrow it could redirect to a competitor’s site, or a porn domain. Doorway pages have the potential to be portals to a sort of search engine hell.

Another blackhat technique is cloaking, or creating shadow domains. These techniques differ slightly, but both subscribe to a common tactic: creating keyword-rich sites designed for search engines, but which human eyes will never see. In the end, both techniques reveal one set of content to search engine spiders, and something altogether different to the end user. This violates search engine guidelines, as well as one of the first principles of SEO: Design sites for users, not for search engine spiders.

Finally, follow the money. Your money. You have a right to know where, and for what, an SEO is spending it. Organic search differs greatly from paid search advertising, which is temporary. If you’re paying for organic search rankings, don’t be deceived by results that appear—temporarily—in the paid search advertising section of a search results page. That’s not organic optimization—it’s advertising.