Mostly so I don't forget. I fixed Midori's windows laptop a while back. After finding 0 viruses and others nasties, I couldn't explain why it was so jumpy and crappy. During the virus scan I'd noticed some disk errors and after fruitless messing with SMART I ran into hdrecovers which reads every sector of the disk and tries to provoke the disk into declaring a bad sector as irreparable. The disk then marks it as such and replaces it with one from its stash of spare sectors.
Surprisingly, after "fixing" about 10 sectors, video stopping stopping and audio stopped being randomly distorted. For whatever reason, these sectors were upsetting windows but they clearly weren't actually important because when they are fixed, their data is lost forever.
I'm about to give it a spin over another disk that had been causing problems.