There are times when reinstalling OS X seems like it might be the perfect/only/desperate thing to do.
Justin Pot discusses various reasons you might want to do it, including:
- Why Not Just Reinstall Regularly?
- Everything Is Just… Broken
- When Your Mac Is Slow
- You’re Selling or Giving Away Your Mac
MakeUseOf has the whole story here: Mac Users: Is There Any Good Reason To Ever Reinstall OS X?.