How to Deal with Hidden Text or Links on a Web Page
When text or hyperlinks on a Web page are invisible to users but can be read by a search engine, that’s considered spam. Having hidden text or links is an easy way to get banned from search engines, which is very bad for your Web site.
Here's what you should do when you run across hidden links:
On your own site. Make sure you don’t have any hidden text or hyperlinks on your pages. Drag your cursor over your pages or press Ctrl+A to select all of the page content to make sure it doesn't contain hidden white-on-white elements. You also should make sure your photos and other large elements aren’t covering vestiges of older versions of your page.
On other sites. If you detect lots of hidden text or hyperlinks on another site that’s ranking decently in the search engines, it’s a sure bet the search engines haven’t discovered it yet. Search engines crack down hard on this type of deliberate spam, and may even ban offending sites from the search engine’s index (the database of Web page information that the search engine maintains). You may want to report a site using hidden text or links to the search engines as spam.
Spammers hide text or links from site visitors by using the same font color as the background color (such as white text on a white background), by positioning the text outside the visible page, or by layering an image or other element on top of the content, thus hiding it from site visitors.