I remember I once used the "Cleansweep" cleaner. It ****ed things up so badly, I had to reinstall Windows then reinstall every application.
God, I hate the Windows Registry! Yeah, good design there - a huge monstrous convoluted mega-file which is essential to Windows, yet any application can puke data into it (without your knowledge or permission) anywhere they want - encrypted even - and you have to risk your entire computer installation if it isn't removed correctly. Not only that, but even nicely behaving (non-evil) applications are nearly impossible to back up because of all the crap that's stored there. (you can save individual registry keys or trees, but you have to find them first and do it manually)
To use a greenhouse analogy - application install on Amiga is like having each plant in its own pot, separate from the others (just the occasional root tangling on the bottom). If you don't want one plant, you just throw away the pot.
On Windows, it's like cramming every plant into the same pot, their roots intertwined, everything tangled and woven in, stems attached to other stems with elastic bands and leaves attached to the central stem with sticky tape. If you want to remove something, you've got to rip the ****ing thing out, losing leaves and root pieces in the process.
(...and do it enough times and the central plant, dying and missing leaves, says, "**** this, I'm out of here!"... and then you see a blue screen telling you to reinstall Windows)
