I have been a user of Revo Uninstaller (free) for sometime and find it does a very good cleanup job with typical applications. Today I wanted to clean up my machine a bit more so I proceeded to remove Visual Studio 2005 with Revo Uninstaller. The VS installer removed the app with no issues, then Revo reported about 20,000 leftover registry keys. I am used to basically just see Arpcache and Muicache… since I am not a registry expert I had no clue about most of the 20,000 listed.
So I backed up the registry then let Revo remove the 20,000. It next reported about 1500 leftover files which included my Microsoft Office applications(!) that I knew it should not be touching. So I did not delete any files with Revo. Suspecting that some of the removed keys were also Office-related, I tried to open Word and Excel, both of which knew something was up, as the installer kicked in (albeit just briefly) for each of them. At this point, since I knew there were issues, I just restored the registry and I am now (seemingly) running OK.
My question, then: When is it safe to trust Revo Uninstaller?
As a seasoned software professional, my own answer to this would be the obvious "When the keys it reports are something you understand and know are safe to delete" but then that makes Revo of little use except to registry experts, does it not…?
Best Answer
My answer would be never.
Never trust an automated application to safely clean a windows registry, always always always back it up first.
You should check out this artcile on registry cleaners that points out that removing orphaned registry entries does not actually offer any performance gains, so why bother doing it.
I suspect in 99% of cases it would be fine. Office and VS probably share some basic informational or settings keys because they are both from MS, so that's probably where Revo got confused. My guess is that in this case you probably would have been fine to just carry on with the removed keys and it wouldn't cause any significant problems beyond just requireing you to reset some settings, but always make a backup and hang on to it until you can be certain your system is working fine.