How to Deal with Unrelated Keywords
Some Web sites deliberately use keywords that are not related to the image, video, or other content that is supposed to be described, in the hopes of increasing traffic; this is a form of spam. Cleaning up a mess made by unrelated keywords is pretty simple — just follow these guidelines:
On your own site. Make sure your page content is cohesive, with text, images, videos, and so on all focused on the same subject and keywords. An image’s Alt attribute (brief description of the image included in the HTML) should accurately describe the image; each page’s Meta data (HTML tags the spiders read that are supposed to describe the page) needs to contain keywords that are also used in the page text users see, and so forth.
You rank better in the search engines with focused content anyway, so this is good advice all around.
On other sites. You can view the page source code to see what’s going on in another site’s HTML. If you see Alt attributes or Meta data that’s full of unrelated keywords, they may just be remnants of older versions of the page that never got cleaned up. But if it looks like they’re doing it intentionally (there's no hard and fast rule here, so just go with your gut), it can be reported to the search engines for their investigation.
Including keywords that have high traffic (query) counts but are not part of that page's content sometimes hurts your rankings, and never helps them. Avoid using keywords that do not relate to your content, and be sure that all words that are displayed on the page contribute to your SEO project.