I'd say at least 25% of the OS X apps I try have an installer and therefore require an uninstaller that often doesn't exist. Usually someone on a forum somewhere lists a sequence of terminal commands required to remove an app and it's background services. If I'm lucky.
Happened to me several times in the last two weeks alone. I vaguely remember it took me ages to get VMWare or similar off my machine.
Well all of my applications are superficial apparently, because apart from Little Snitch I can't think of one I'll need an uninstaller for. And LS is a special case.