This image should illustrate the point I'm trying to make:
I suggest that when the community generally disagrees (3 rejects vs 1 approve, 3-5 recommend deletions vs 1 looks good, etc.) too many times, the reviewer's privileges be suspended for some time.
I think a good algorithm would be this:
if (disagreements / total reviews >= 0.25) { suspend user from reviews }
Although the number may be tweaked as the community sees fit.
I think this might help (but probably not solve) the robo-reviewer problem. 416 approvals and 4 rejections is just crazy.