not using time machine is a big mistake , it is after all the best feature of OSX snow leopard
and app cleaners can be helpful , but you need to know what they(you) remove and not just dragging a app in the app cleaner can hurt OSX if you are a bit careless , as these app cleaners can remove important files too , think about these tools as a hammer , useful yes , but all to easy to hit your thump if you are a bit careless
any app is only as good as the user