I have nothing against uninstallers really, including this one from Ashampoo, though I strongly disagree with the marketing pitch they use, e.g., Ashampoo: "Remove software down to the last byte..." Bull***t! I've monitored software installations using InstallWatch Pro, Regshot2, and Ashampoo UnInstaller, all at the same time, and Ashampoo UnInstaller does not always revert absolutely every change.
In all fairness, it can sometimes be very difficult to judge whether removing a file or registry entry will break something -- I've broken Windows removing registry keys that an app added -- so it's probably impossible to write rules dictating what can always be removed safely without skipping whole categories of files and registry entries. Logging a software install in something like Ashampoo UnInstaller helps, but you can't always remove &/or revert every change -- that's how I broke Windows recently [I was prepared for it and had a backup ready which I restored] -- so expect the uninstaller to error on the side of caution. If you install whatever software, logging the installation in Ashampoo UnInstaller, you will probably revert *most* of any changes if you use Ashampoo UnInstaller to later remove it, and you *might* remove more than if you had just uninstalled that software normally. There's also a chance that its registry cleaner might break something unrelated, same as running any registry cleaner.
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One of the comments on the download page for today's GOTD mentioned an unusual case, where a Paragon software rep told him not to use uninstallers with their backup app. One way it's unusual is Paragon's sorta out of the game nowadays -- their HDM 16 [~2018] was a total redesign, and not bad, but version 17 [~2020] pretty much fails all the way around, and they haven't done anything with it since, concentrating on the corp. market. Another way it's unusual is the rep told the OP that using an uninstaller might mean a copy of Paragon's HDM would not activate later on. I can see why you'd want to uninstall it to install a newer version -- Paragon's HDM installs side by side with older versions -- but running an uninstaller would be way overkill, since 90%+ of any leftovers would just be reinstalled with the new version. Anyway, for an uninstaller to prevent future activations it would have to remove a somewhat hidden file or registry entry that, used in combination with another, remaining [overlooked] file &/or registry entry, could trigger the software to shut down its activation routine. Only a few apps have ever gone that far trying to prevent piracy. And those apps, including Paragon HDM, also provide a mechanism where you can remove the software's license from a copy of Windows so it can be used elsewhere. IMHO it's best to avoid software from any company that values their paranoia more than their customers' experience, but that's me, and if you must use it, when you see a way to remove the license from that copy of Windows, use it before uninstalling that software.