I suggest to completely remove negative reputation for anyone except mods. A mod usually really knows why he gives negative rep. I guess 80+% of the reputation, no matter if negative or positive is just abuse/spam. The negative ones because people don't like that secrets are shared or to make competition or other members look worse. Positive rep is shared between members just to look better. Also reputation can be non-anonymous again once negative rep is removed, actually I'd find it good if everyone could see who gave positive rep to someones account and why he did so. That would further reduce the reputation spam.