In the most current patch for 1.9.4 (future 1.9.5) it is virtually impossible to have any hidden grades in the gradebook if you use SUM or SWM.

• If you hide grade items - they are now included into the Total aggregation for both student and instructor (in regular 1.9 they were included only for the instructor)
• Solution to move such items into a separate hidden category does not really work, since the Course Total still includes those grades and confuses students (so instructor has to use weights, I guess)
  What would help here, is an option to hide Course Total.
  However, if you hide Category Total = you hide the whole Category from the student view, and if you hide Course Total = you hide the whole gradebook.
  Screenshot is attached. I have hidden the Total for Category 1 there, but in the student view the whole category is gone.

P.S. And, by the way, if you hide just one item - layout of the User report in the student view is severely misaligned. Please see the second screenshot.