Do I need to bother about correctly uninstalling Mac software?

"For most Mac software, using AppCleaner and or AppZapper is sufficient - it removes the software, as well as the preferences, your customization, etc. Dragging the software to the trash bin is also good enough - as the left-behind preferences will not affect anything but disk space. In fact, you might want to keep those preferences in case you decide to re-use the software in the future.

The tricky software to watch out for are usually those huge, complicated programs, which embed kext extensions, or pepper the system with files all over. For example, VMWare, Parallels, Adobe CS3, etc. For these category of software, try to use the official uninstaller as much as possible."

"It's not exactly very complicated to uninstall an app in Mac OS X. When you drag it to the Trash it really is gone, so it's uninstalled. The problem is that most apps also have preferences and other auxiliary files; they are nt deleted when you remove the app.

However, there are quite a few apps that remove the files left over. One such app is AppTrap. It does it's job just as well and is free. When you move an app to the Trash, it asks you if you also want to move all it's preferences and customizations as well. Simple and effective :). Here's what it says on the Apptrap site:

The feature Apple forgot

OK, here's a fairly simple idea: what
if applications could be uninstalled
as easily as they are installed, in
other words, by drag-and-drop.

The exact opposite would have to be...
dragging the application to the trash.
Ah, there you go! This is exactly what
AppTrap does. Whenever you drag an
application to the trash, a dialog
window will pop up, asking if you want
to delete the associated system files
too. Simple as that.

So you see, using something like Apptrap really does make it seem easy. It's just a few extra files deleted along with the app.

Just as a quick note: AppTrap is no longer developed; however, it works perfectly in Leopard and the project has forked with the original authors blessing."