It really depends on how advanced the method of cloaking is that your using to be honest. Some lower levels of cloaking will get caught pretty easily, like doorway pages. But most .htaccess methods of cloaking are hard to spot.
For top of the line cloaking go with fantomaster, we have been using that for quite some time and its probably the best you can possibly get, but its a pain in the ass to get setup correctly, and will cost you a fortune. But once its setup properly it's a beast.