1st, do a WoT and only take reports from actual accounts.
I always wanted to create a way to report a report as incorrect so that there is some punishment for WoT accounts if they lie. Then you can score how trustworthy a reporting account is by how many incorrect reports it has.
Of course, anyone can also do an incorrect report of an incorrect report. But I think a good WoT analysis can sort them out. If reporting groups are fighting each other, both of them go down.
Need to think more about this game theory approach.