Why would one want to cloak their pages? What benefit does it give and can anyone give a situation to demonstrate when a black-hatter would use it?
Overall, it shows the user a different version of their page so that it looks appealing to them. But when it sees the IP of a Search Engine (Google, MSN or Yahoo!) they show a different page with more keyword concentration and SE optimization to rank better in search engines, a format that visitors won't necessarily like
Cloaking a web page itself is usually a black-hat strategy, but it doens't really work that well anymore. Cloaking links themselves is obviously the best way to go when promoting affiliate products though.
SEO is still SEO, despite how you choose to do it...It's your choice whether or not to cloak, don't avoid cloaking just because somebody tells you to do it - if you think you can do it efficiently go for it