Webmasters can detect the IP addresses of Search Engine Robots and there are plenty of updated lists out there. The devious web site owner simply looks at the IP address of the spider and when confirmed, it delivers a page designed just for the search engine – without your links!

This is by far the most popular and hard to detect method of cheating and is commonly used. Some people suggest looking at Google’s cache of the site with your link on it, but if the website owner requested that Google (or others) not cache their website, then this will not work.

How to discover these Hidden Links

Look at other links on the page that will have your link, pick one (any one) see if it has a backlink from Google; if there is no backlink and Google’s does not have a cache of the page containing the links, then personally, I would skip this site!

Below you will find some examples of hidden links; all link to google.com. Let’s start with the table link example?

www.microsoft.com

This is an example of a hidden link using styles. I left out the pointer for obvious reasons:

www.microsoft.com

This is an example of sending the click to another internal page, then passing the click on to the site:
www.microsoft.com

Search Engine Ranking

These are just a few examples provided for your viewing enjoyment. There are many more, but these are the most common methods in use today.

If search engines like Google do not have a cache of the site you’re thinking about exchanging links with, and things just don’t feel right, then you may want to just skip the site and move on.

Misc: See Google’s warnings about using the rel=nofollow tag also used to prevent PR from passing.