One of the key ways to increase your search engine rankings and traffic is to increase the number of websites that link to your website. The number and context of such links, and the quality and relevance of the sites that link, help Google and other search engines decide how highly each of your website's pages should be ranked for the search terms being entered.
For this reason, companies that offer SEO as a service usually offer advice or services related to increasing the number of links to your website. Reputable companies will only strive to increase your links via "white-hat" methods - for example, writing a press release about your product or service and distributing it for publishing (complete with links) on many websites, or answering a forum post on a website related to your industry with a link to a page on your website that is of actual value to the forum poster asking the question. While both of these methods may result in links that would not otherwise have existed, when carried out correctly and with care they do not create a false impression when Google tries to interpret your website.
Such "black-hat" offerings are normally quite easy to spot because they normally offer guaranteed ranking positions in a short space of time, and are normally cheaper than reputable companies. Businesses that have only just created a website, and who have little knowledge of the industry, can easily fall prey to such offers and an entire industry has been born as a result.
It's not difficult to find companies or individuals that claim to be experts at increasing your search engine rankings. In many cases they are experts at doing just that, but most of the time they are not experts at optimizing your search engine rankings holistically. Such services normally guarantee a specific search engine ranking for a specific keyword, and the customer would be contracted to make payment once this has been reached, and there's a good reason for that. In most cases, in the days and weeks that follow this milestone your website will almost disappear from search results completely. This is because Google has detected spam activity and has penalized your website. Such companies are not interested in your long-term success.
Even large companies can apparently fall prey to the lure of a shortcut to search engine success - the high-profile UK-based flower delivery business Interflora purchased links to their website from a variety of major newspaper websites and was subsequently removed from Google's index completely. "Google tends to look at buying and selling links that pass PageRank as a violation of our guidelines", said Matt Cutts, head of the Webspam team at Google. Even though Interflora's website returned to search results after only 11 days, Google has been keen to point out that actions against repeat offenders will get "more and more severe".
And it's not just paid links that Google is clamping down on. "Link farms", which have long been the primary tool of the "black-hat" SEO industry, are now being detected more effectively by Google. One such service, Anglo Rank, actually claimed in it's promotional material that it had "absolutely no footprints", meaning that they thought Google would not be able to detect that websites were using it to artificially improve their search engine rankings. In response, Google's Matt Cutts publicly ridiculed this claim on Twitter, and websites using the service received penalties shortly after.
It is therefore clear that even if Google is not able to detect such networks automatically, it is using human intelligence and investigation to uncover them. Despite this, and in keeping with the "black-hat" approach, the owners of Anglo Rank said they will "relaunch this service and make It even better and stronger than before".
If you are ever considering paying for an SEO service, always ask yourself one question: "Does it seem too good to be true?". If the service seems to offer fantastic results in a short space of time, and for low cost, then the company or individual is almost certainly using "black-hat" techniques - which means the only thing that is guaranteed is that your search engine rankings will actually suffer in the long run. SEO that works is a long-term project that requires genuine effort.