Making reps possible to see only for other admins (than the one who got rep) should work. I guess it'd need some vBulletin surgery fun though, wouldn't it? Btw, I'd probably feel some discomfort negrepping admins too. Never seen such a need, as I hardly ever even negrep anyone and the admins seem to be doing a good work, but I can understand Newspaz's point of view.