Hidden Links

There are at least FOUR ways spammers link build and hide the links, all of which previously worked successfully  on all search engines, but are now penalised by the google algorithm which is clever enough to find them (unlike Yahoo? and Bing?) 

1) Hidden Text which forms a link, and is the same colour as the background

2) A link that does not react or change colour when the mouse cursor passes over it, so the user does not know it is a link

3) A link that is disguised as a button, which does not react when the cursor moves over it (mouse over).


In a public forum, Matt Cutts (Google) explains why Google has barred BMW  from its index until it removes cloaking  

Deveopers should  do a free search for 'free check for cloaking', they should find an online program that helps them check that any site they are 'developing' site appears exactly the same to the search engine as it does to the viewer

What is cloaking?