The cloaking system works by detecting search engine spiders via spider name or IP address. By comparing the IP address of the site visitor to a database of IP addresses of search engine spiders, the cloaking program determines whether or not a visitor is a search engine spider. (Incisive Interactive Marketing LLC)

Marketers may use cloaking to draw users to pages that have many ads but little to do with what the person was searching for. (QuinStreet Inc.)

Most search engines will immediately remove and sometimes blacklist a site that is discovered to be cloaking. They do this because cloaking is usually intended to completely fool the search engine's algorithms and programming that determine what makes a site rank high or low in that engine. (About.com)