Warning Such tools are not toys! You will destroy your system very thouroughly if you don't know what you are dooing! Unless you realy know what you are cleaning exaclty and how it efects every other aspect of your windows than you might use such tool properly. If your only contribution to the cleaning process is that you click on a button like "select all" then you are activly destroying your windows! I know from experience on supporting normal consumer pc that such "cleaning tools" do more harm than good. The standard settings are very good for an average Joe PC-user and some small settings which are in some cases right to do you can do without such "cleaning tools".
To edit the Registry is as quite dangerous step which could end up in destroying your installed system and apps. Most (99.9%) of those applications doing much more harm than good! That also applies to any other tools which are used to change or edit any system files, settings and configurations. If you're not 100% sure to know what you're doing, keep your hand's off from those tools.