Cloaking sometimes can work good, but not every site can come up due to cloaking. The algorithms are changed without letting anybody know about it. And search engines do that to get them to know about the site effects. Also people do fall for bad cloaking temptation if their site is not ranking up, and lose more money to cloakers while getting no results on their website. And once a site gets bad effect, it then continuously gets uncontrollable bad results leading to more fall of ranks. Why people why, you want to use bad ways, if things don't work the correct way?