Search engines clamped down hard and began to establish a system to defeat sites misusing the program. I won't say the program is now deemed illegal by search engines, but it looks like it will end up that way. I will say that if the cloaked page has nothing or little to do with your Web site and search engines discover it, be prepared to be banned. Invisible Text Search engines frown on tiny font sizes and invisible text, which is text the same color as the background of your Web page. These tactics are considered spam and if detected will get your site banned.
Most search engines can detect even the most subtle spam techniques.
If you're attempting to increase search engine rankings, do not use these tactics. If you plan to hire a company to increase search engine rankings, make sure these practices are not used. Look at examples of the company's work. If the company is reluctant or won't show you results, shop around. If you want your banners to sell better, visit BannerTips.