If I had to guess it repairs permissions using disk utility. And maybe defrags the drive.

...should you buy anything from them - or when registering your apps.

Use an address that you won't mind getting hammered at least once every day by them pimping some other product.

The Macolytes need not lose faith in this new revelation. There is no contradiction in the existence of this cleaner app and the divine perfection of a Mac. All this app does is purge the corruption caused by unclean user's interaction with the divine artifact.