I've had great success polishing damaged aluminium parts but if the scratches are deep or you don't use the right sandpaper / polishing compound that might require a lot of elbow grease" Heck... even if you have the right tools! One of these days I'll get a cheap buffing machine such as this one : http://www.pjtool.com/6buffingmachine.aspx

Not only will it save time and fingers but it also does a more consistent polish.