Although search engines do a good job sifting through the millions of pages available, it does not mean they always get it right. There are non-relevant sites which make it through, requiring a little more digging, but each search engine does its best to find what you are looking for. It is because of these instances, it becomes very important to use specific terms so as to not pull up terms unrelated to your subject. A Search engine cannot ask questions to focus its search. Unlike humans, they do not have the ability to hold accountable web pages which have spammed or to rely on past experiences of a company.
Search engines use their own set of rules in deciding the relevancy or reliability of a web site.
For example, one of the main rules involves the location and frequency of keywords. In deciding the top rankings, search engines will look for pages with the keywords located in the title or the first paragraph, versus at the bottom of the page. Although search engines follow the same rules to a certain degree, they all have their own method meaning they may come up with different results for the same keywords. This is why it is so important to find out how to get into a search engine top rankings. Here at Oneupweb, it is our job to know what each search engine deems important in ranking web sites.