I use Revo when I run into a program that has a crappy unistaller. I prefer the Add/Remove control panel option, but Revo has that option to.
I use Revo to see what the uninstaller has left behind. Sometimes it's a lot. Sometimes what the uninstaller has left behind gets removed during a reboot. Add/remove programs is usually sufficient.
I recently installed Revo and used it once or twice. I think I was uninstalling Adobe Reader. Like others have stated, I prefer Add/remove but having Revo around is a good thing.
Very often use the Windows one in Add/remove programs. If the program has an uninstaller itself in its program menu entry...I'll often use that. For botched uninstalls....I've used Revo quite a few times as a good 3rd party alternative. Have also turned to the Windows Installer Cleanup Utility.
Been using Your Uninstaller since 2003 (purchased "lifetime" license at that time). I have found it to be well worth the initial price - good at removing all traces of the program, or at least as I can tell.
When things go wrong I often try to correct the corruption (by intensely hunting down remnants, especially in the registry) , but often times I find that it is less time consuming to Re-image or Re-install the OS to avoid the inevitable corruptions when a incomplete uninstall occurs. I think that in order for an uninstaller to work correctly it must be installed prior to any applications to work as intended. If not the registry will be chock full of what should-have-been-removed remnants of the wanted uninstalled application. Uninstall programs may remove all perceived "functional" remnants of the program but still retain registry items that may eventually "contaminate" the workings of the OS later on. These items may count in the hundreds. If a pristine state is wanted in these cases full re-imaging or re-installation is the only satisfactory solution (especially if one is a purist or has OCD).
None other than the program's own uninstaller or just rollback the system to a previous state before product was installed especially when testing.