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...?