This latter rogue application that promises to clean up your Mac and make it perform faster goes out of its way to install files in difficult-to-delete places. Moreover, in this example the supplied Uninstaller app will not necessarily remove all the unwanted crud after uninstalling the app.
You must be vigilant here for unexpected launch daemons ('launchd' files) that allow hidden applications to automatically launch at boot.
Experienced Mac users can use the command-line Terminal.app to seek out and remove unwanted fragments. A slightly less dangerous way is with a graphical file finder such as the marvellous Find Any File, which will find all the hidden files that Apple conceals in normal Spotlight searches. Nevertheless it must still only be used with caution as it is possible to delete essential system files. In general, be wary of deleting anything from your Mac that requires you to type in an administrator password.
How to uninstall a software application from Mac OS X: Shareware options
Finally, there are shareware utilities that promise to do all the hard work of tracking down errant app files and delete them for you.
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